Determination of precious metals in rocks and

Determination of precious metals in rocks and ores by microwave plasma-atomic emission spectrometry for geochemical prospecting studies

Vysetti Balaram1,*, Dharmendra Vummiti2,4, Parijat Roy1, Craig Taylor3, Prasenjit Kar2, Arun Kumar Raju2 and Krishnaiah Abburi4

1CSIR–National Geophysical Research Institute, Hyderabad 500 007, India

2Agilent Technologies, CP-11, Sector-8, IMT, Manesar, Gurgaon 122 051, India

3Agilent Technologies, 679 Springvale Road, Mulgrave Vic 3170, Australia

4Department of Chemistry, Sri Venkateswara University, Tirupati 517 502, India

Methods were designed and developed for the quanti-tative determination of Au, Ag, Pt and Pd in several rock and ore reference samples by a new analytical technique, microwave plasma-atomic emission spec-trometry (MP-AES). Two-gram samples dissolved in 100 ml using aqua regia digestion was directly used without any separation or a pre-concentration step for the determination of Au and Ag. On the other hand, NiS fire-assay technique followed by tellurium co-precipitation separation and pre-concentration step was adopted on 5 g samples to separate Pt and Pd from rock matrix for the determination of these two elements. Detection limits obtained are in the 0.5–5 ng/ml range for all these metals. MP-AES detection limits were compared with those of other well-established techniques, such as F-AAS, GF-AAS, INAA, ICP-AES and ICP-MS. The results obtained for Au, Ag, Pt and Pd were compared with those obtained by well-established analytical techniques such as F-AAS and ICP-MS. Precision and accuracy of the methods were demonstrated using replicate analyses of some international precious metal ore ref-erence materials. Precisions of <5% RSD at practi-cally 10–200 ng/ml levels of these elements in solution with comparable levels of accuracies were obtained which show good agreement with certified data. As there is limited literature on the application of MP-AES in geochemical and mineral exploration areas, this study forms one of the first application studies in these areas.

Keywords:Fire assay, geochemical prospecting, MP-AES, precious metals, rocks and ores.

P RECIOUS metals (Ru, Rh, Pd, Os, Ir, Pt and Au; some-times Ag is also added to this list) are used in a variety of applications.Concentration and distribution of Au, Ag, Pt and Pd in various types of rock formations have attracted enormous interest from explorers in recent times due to their rising demand in the technology sector owing to their applications as catalysts, biomedical tools (e.g. anti-cancer drugs), corrosion-resistant materials, high electrical conductivity materials, micro electronics and also in jew-ellery. As a result, the interest in better understanding the chemistry, mineralogy and geological occurrences, min-ing and extraction of these metals has been growing1. Ac-curate and precise determination of Au, Ag, Pt and Pd in hundreds to thousands of different types of rock and ore samples is required in exploration, mining and extraction activities2,3. Currently, a range of elemental analytical techniques, including flame and graphite furnace atomic absorption spectroscopy (F-AAS and GF-AAS), induc-tively coupled plasma atomic emission spectroscopy (ICP-AES) and ICP mass spectroscopy (ICP-MS) are available for such studies. Despite striking advancements in analytical methods in recent times, a few elements such as Au, Pt and Pd remain the most poorly studied mainly due to the analytical difficulties in generating accurate data for these elements in rock and ore matrices, where the concentrations encountered are usually very low. In general, determination of these metals in geologi-cal samples is a two-step process though direct determi-nation is also possible in some situations4. The first step involves preparation of representative samples and then separation of these elements from rock/ore matrix by a separation and pre-concentration technique such as nickel sulphide fire assay. The second step involves measure-ment of concentration by an instrumental analytical tech-nique5. In recent times, yet another promising analytical technique, called microwave plasma-atomic emission spectrometry (MP-AES), which uses nitrogen as plasma gas, has been introduced by Hammer6 with commercial instruments introduced by Agilent Technologies Inc., in 2011. Not many application studies have been reported using this technique so far, except a report on a prototype

*For correspondence. (e-mail: balaram1951@https://www.wendangku.net/doc/125019952.html,)

Table 1.Microwave Plasma-Atomic Emission Spectrometer operating parameters

Agilent 4100 microwave plasma-atomic emission spectrometer with 4107

nitrogen

generator Plasma conditions

Power of magnetron output 1 kW

Gas flows

Plasma gas flow – nitrogen 20 l/min

Intermediate flow – nitrogen 1.5 l/min

Pre-optics protection gas – air 25 l/min

Nebulizer pressure 140–240 kPa (optimize for each element)

Nebulizer OneNeb inert concentric for HF and high TDS solutions

Spray chamber Double-pass glass cyclonic

Torch Quartz torch

Plasma viewing Axial

Acquisition parameters

Sample uptake delay 8 sec

Stabilization time 60 sec

Read time 5 sec

No. of replicates 3

Background correction Auto or FLIC (fast linear interference correction)

Optical system Czerny–Turner design monochromator with 600 mm focal length and fixed entrance slit

Detector Back-thinned solid state CCD detector (532 × 128 pixels)

Analytes (wavelength) Au (267.595 nm), Ag (328.068 nm), Pt (265.945 nm), Pd (363.470 nm)

instrument by Zhang and Wagatsuma7 on the matrix effects of easily ionizable elements and an application re-port on the determination of precious metals by Taylor8, though there have been a few other studies9–11 on the mi-crowave-induced plasma generated by other gases such as argon and helium. There is not much literature available at present on the application of MP-AES in geochemical and mineral exploration studies. In this study, an attempt is made to determine Au, Ag, Pt and Pd by MP-AES in several international geological precious metal reference materials by adopting aqua regia digestion (for Au and Ag) and nickel sulphide fire assay followed by Te co-precipitation method (for Pt and Pd).

Experimental

Instrumentation

The Agilent 4100 MP-AES with 4107 Nitrogen Generator was used in this study. The operating parameters used are presented in Table 1. This relatively new and simple instrumental technique is a fast sequential multi-element analytical technique that has a microwave-induced nitro-gen plasma as an excitation source and optical dispersion and detection components similar to ICP-AES. This in-strument uses a microwave excitation assembly to create a concentrated axial magnetic field around a conventional torch. This focuses the microwave energy where it is needed to produce a toroidal plasma with a cooler central channel that is suitable for stable introduction of liquid samples using a conventional sample introduction system. The principle of this technique is similar to any other emission technique such as a flame emission technique or the well-known ICP-AES12. The intensity of each emitted line will be directly proportional to the concentration of a particular element. More details of the MP-AES atomic source, optical system and detector of the instrument are provided in Hammer6.

Precious metal geological reference materials used Sixteen international geological reference materials were utilized in this study for the determination of Au, Ag, Pt and Pd. Table 2 presents details of each sample, such as the rock/ore type and source of these reference materials.

Materials and reagents

Anhydrous sodium carbonate, disodium tetraborate, sul-phur, stannous chloride and fine granular quartz (silica), all of AR-grade quality produced by Merck (Darmstadt, Germany), Ni powder (-100 mesh) of 99.999% purity from Aldrich Chemical Company (Milwaukee, Wl, USA) and tellurium powder (-385 mesh) of 99.998% purity from Alfa-Aesar (Wardhill, MA, USA), distilled HNO3 and HCl (Merck) were used for sample preparation. These high-purity reagents and acids were chosen to minimize the procedural blank values. Millipore purified water (18 MΩ) was used in all studies.

Sample decomposition methods

For gold and silver in ore samples:After roasting at 650°C in a muffle furnace, 2 g each of samples was weighed into individual 100 ml Borosil glass beakers and

Table 2.Details of precious metal reference materials utilized in the present study, type of rock/ore and their source Sample name Rock type Source

SARM-7 Precious metal ore MINTEK, P/Bag 3015, Randburg 2125, Republic of South Africa

PTC-1 Sulphide CCRMP-CANMET-MMSL (NRCan), 555 Both Street, Ottawa, Ontario

K1A 0G1, Canada

PTM-1 Ni–Cu matte solid -do-

WMS-1 Massive sulphide -do-

PTC-1a Cu–Ni–sulphide concentrate -do-

WPR-1 Altered peridotite -do-

S9 Gold ore ROCKLABS LTD 161 Neilson Street, Auckland, PO Box 18-142,

Auckland, New Zealand

Ox 15 Gold ore -do-

Ox 2 Gold ore -do-

S-6 Gold ore -do-

S-5 Gold ore -do-

Ox-9 Gold ore -do-

Ox-11 Gold ore -do-

Ox-12 Gold ore -do-

Ox-13 Gold ore -do-

BND 3401.01 High-grade gold National Physical Laboratory, New Delhi23

40 ml of freshly prepared aqua regia was added to each. These were then placed onto a hot plate at 200°C. The content was reduced to 10 ml after which 20 ml of freshly prepared aqua regia was added. The solution was heated until the volume reduced to 5 ml. The final solution was filtered and made up to 100 ml and stored in HDPE bot-tles. A couple of reagent blanks were also prepared in the same manner. Six replicates of each sample were dis-solved in each case using the above sample dissolution procedure.

For platinum and palladium (NiS fire-assay decomposi-tion followed by Te co-precipitation method): Five grams of the finely powdered sample, 2 g of Ni, 1.2 g of S, 20 g of Na2CO3, 80 g of Borax, 6 g of SiO2 and 1.5 g of CaF2 were mixed and transferred into a fire clay cruci-ble. Under reductive conditions, the sample was fused in a preheated furnace for 80 min at 1050°C. The melt was then quickly poured into an iron mould and allowed to cool for an hour. The NiS button was separated from the slag and crushed into small chips (>1 mm in diameter) in an agate mortar. The NiS chips were transferred into a 250 ml beaker and dissolved with 100 ml of purified conc. HCl at 150°C over a hot plate, until the volume reduced to about 50 ml and dissolution was complete. After reducing the volume of the solution to about 50 ml, an equal amount of deionized water was added and the solution was heated to boil on a Bunsen burner. Then 2 ml of 1000 μg/ml Te was added to the completely dis-solved solution, the solution was stirred and 5 ml of 20% SnCl2 (freshly prepared) solution was added drop-wise. The black Te-precipitate formed was heated to coagulate at about 80–90°C for 60 min. The solution was then cooled and filtered through a 0.45 μm cellulose nitrate membrane filter paper using the Millipore vacuum filtra-tion system, for a quantitative transfer of the platinum group elements (PGE)-containing Te-precipitate onto the filter paper.The residue was washed with 10 ml of 10% HCl and followed by washing with few millilitres of deionized water. The filter paper was transferred to a 100 ml clean, dry glass beaker and 4 ml of freshly pre-pared aqua regia was added. The contents were heated on a hot plate at 150 ± 10°C for 2–3 min till the PGE residue dissolved and a clear solution was obtained. The solution was transferred to a 50 ml volumetric flask and the vol-ume was made to 50 ml with deionized water. These final solutions were immediately used for determining Pt and Pd by MP-AES. Six replicates of each sample were dissolved in each case using the above sample decompo-sition procedure.

Analysis

During the analysis, the nebulizer system was washed with 1% HNO3 and deionized water in that order in each case and the data on each sample/standard/blank were acquired after 60 sec of nebulization to stabilize the plasma. Procedural blanks, calibration solutions, sample solutions and reference sample solutions were analysed in that order.

Results and discussion

Precious metal exploration studies usually involve vari-ous stages, such as reconnaissance study, detailed follow-up, anomaly delineation and target definition, resource estimation and reserve calculation. In all these stages, documenting Au, Ag, Pt and Pd distributions in a particu-lar area and identifying anomalous high concentrations

are essential to locate and develop precious metal mine sites and to understand the dispersal of these metals in geological systems. Large numbers of rock and ore sam-ples collected in such exploration programmes are usually analysed for these elements. Hence, the methods deve-loped must be simple, easy, cost-effective and environ-mentally friendly.

Aqua regia is a 3:1 mixture of HCl and HNO3 and is a strong oxidizing mixture that can attack Au, Ag, Pt and Pd. It can also decompose sulphides, including pyrites, arsenides, selenides and some Mo and W minerals13. Although some workers14 preferred use of HF during decomposition of the sample to recover Au completely, earlier studies in our laboratory4 revealed that, in a major-ity of the cases, significant differences are not observed in the extraction efficiency of gold when HF was added to the reaction mixture. However, there have been several reports5,15 that aqua regia attack is virtually completely efficient in solubilizing Au and Ag from geological sam-ples, particularly when the attack is made after roasting the sample at 650°C. It is also possible to vary the sample size from 2 g up to 20–50 g depending on the sample homogeneity, target elements and their expected concen-trations. Since all the gold reference materials used in this study are well-homogenized samples, 2 g sample size and only aqua regia attack were preferred.

Although both lead and NiS fire-assay methods for the determination of Au, Pt and Pd are probably the most reliable methods of separation and pre-concentration sample preparation for analysis of most geological mate-rials16–18, only NiS fire assay was chosen in this study for the determination of Pt and Pd. As all the samples taken in this present study are well-known PGE reference mate-rials, sample homogeneity was ensured, and hence, 5 g sample size was used for the NiS fire-assay procedure. Because of the heterogeneous distribution of PGE in various types of rocks and ores, separation and pre-concentration of these elements by the NiS fire-assay technique is best suited as it can handle larger amounts of sample (5–50 g). The Te co-precipitation step enhances the recovery of PGE.

Spectral interferences, calibration strategies and linearity and results

Spectral line interferences in emission spectrometry can severely affect the accuracy of minor and trace element determinations, particularly in geological samples because of their complex nature. For all elements in this study, the most sensitive wavelengths in each case were utilized. In general, the interference effects from adjacent lines can be minimized by using a high-resolution spec-trometer in the instrument, decreasing the width of the slits or using higher spectral orders. A high-resolution spectrometer (resolution <0.035 nm) has a definite advan-tage for the analysis of spectrally complex materials. However, there is a practical limit to the resolution that can be achieved. This is determined by the natural line widths and the extent of broadening. Furthermore, even with a high-resolution monochromator, there may not be sensitive lines free from spectral interferences that can be used for trace element determinations in complex materi-als19. The analytical wavelengths for all four elements in this study and possible interfering lines of other elements present in the sample solutions are presented in Table 3. With the sample preparation procedures followed in the present study, such interference effects were found to be negligible. For example, Figure 1 presents the possible interferences on Pd analytical wavelength (363.470 nm). Possible line interferences from other con-comitant elements are also depicted. As only tellurium and other PGE are expected to be present in the solutions, the expected interference effects from other elements (shown in Figure 1) are found to be negligible in this parti-cular case.

The concentration or working range of an analytical technique is the range of concentration that can be meas-ured accurately without the need to recalibrate or dilute the sample. In order to overcome matrix effects that are generally observed during the analysis of geological sam-ples by a number of instrumental analytical techniques, several methods can be used. Dilution of the sample, use of internal standardization and matrix-matching calibra-tion standards are some of the procedures generally adopted for obtaining precise and accurate data. In the present study, external calibration was performed using solutions of identically prepared international precious metal reference materials (Figure 2) to minimize possible matrix and other interference effects. Out of the reference materials studied here, a few were selected to cover the entire working range for calibration of all four elements in each case (Figure 2). This approach is beneficial in several ways. First, because the dilution factor is the same for all solutions in each case, the absolute (rock) concentration values for each element can be used for calibration so that quantification becomes straightforward for unknown samples. A second advantage is that, the possible errors arising due to dilution will be minimal. This approach also minimizes the possible inter-elemental and matrix (spectral and non-spectral) interfer-ences. The calibration graphs shown in Figure 2 are linear in the concentration ranges of these studies for all four analytes. The linearity in the calibration curves in all cases was found to be better than flame AAS in general. In addition, AAS, MP-AES has the capability to do fast sequential measurement of different elements making it one of the rapid analytical techniques currently available to the exploration geochemists.

Au and Ag determined in 10 international gold refer-ence materials, and Pt and Pd determined in 5 PGE international reference materials are presented in Tables 4

Figure 1.Possible interferences on Pd line (363.470 nm). Resolution <0.05 nm.

Table 3.Possible interferences for Au, Ag, Pt and Pd by MP-AES (resolution <0.050 nm)

Analyte Wavelength (nm) Interference effects by different elements

Au 267.595 Nb: 267.594 nm; Ta: 267.590 nm; Cr: 267.715 nm

Ag 328.068 Rh: 328.055 nm; Sc: 328.078 nm

Pt 265.945 Ta: 265.941 nm; Ru: 265.962 nm

Pd 363.470 Ho: 363.467 nm; Gd: 363.476 nm; Fe: 363.440 nm

Table 4. Concentration (μg/g) of gold in some international geological reference materials determined by MP-AES after aqua regia digestion

Au

(μg/g) Ag

(μg/g)

This study This study

Average Average

Sample CAL 1 CAL 2 DIBK-F-AAS20 RV+% RSD CAL 1 CAL 2 RV+ %

RSD

S9 5.62

5.82

–

5.23

1.3

14.73

15.2

14.72

1.7 Ox-15 6.68

6.87

–

6.98

0.9

20.26

20.08

20.86

2.3 Ox-2 1.84

2.02

1.40

1.42

3.8

BDL

BDL

NA

–

S-6 13.6

13.55

–

13.89

0.5

17.37

17.10

17.08

1.7 S-5 5.30

5.51

–

5,00

1.4

9.49

9.24

NA

1.4 Ox-9 0.52

0.45

0.48

0.46

5.1

BDL

BDL

NA

– Ox-11 3.17

3.47

2.92

2.94

1.4

8.91

9.19

NA

0.7 Ox-12 6.07

6.44

6.59

6.60

1.3

9.69

10.07

10.40

0.8 Ox-13 1.85

2.11

–

1.77

3.6

BDL

BDL

NA

– BND 3401.01 (ref. 23)12.49 12.63 12.22

12.10

0.8 1.08 1.07 1 3.1

n = 6; +Certificates of analysis issued by ROCKLABS, New Zealand; –Not available. CAL1 – Against matrix matching calibration standards;

BDL – Below detection limit; CAL2 – Against aqueous calibration standards; NA – not available.

and 5 in comparison with certified data. Au and Ag re-sults obtained in these studies (Table 4) demonstrate that MP-AES is a powerful analytical technique which allows fast and direct measurement of these elements without the need for adopting any separation or pre-concentration procedures. In general, the MP-AES data for these two elements compare well with reference values, wherever values are available for comparison. The values obtained for Pt and Pd in some of the international PGE reference samples (Table 5) compare favourably with reported values proving that MP-AES is an extremely valuable technique for the detection and determination of Pt and Pd in rocks and ores after separating and pre-concen-trating these elements from the rock matrix by NiS and Te co-precipitation methods. The data for Pt and Pd also compared favourably with those generated by a well-established NiS fire-assay ICP-MS technique (Table 5). These results for Pt and Pd suggest that MP-AES when combined with NiS fire assay can also generate data of sufficient quality for exploration studies.

Another important aspect is that there is an excellent agreement of the data obtained using simple aqueous sin-gle-element calibration curves for both Au and Ag with certified data (Table 4). The data obtained thus for these two elements also match with those obtained by calibrat-ing with certified reference materials (Table 4). For Au, the data generated by this method also compare favoura-bly well with the established DIBK-F-AAS procedure20.

Figure 2.Calibration curves for Au (aqueous and matrix), Ag (aqueous and matrix), Pt (matrix) and Pd (matrix) constructed by analysing refer-ence materials of different concentrations.

This proves that the matrix effects are minimal or negli-gible in the MP-AES technique, at least with respect to Au and Ag in geological samples. On the other hand, such agreement was not obtained in the case of Pt and Pd. More studies are needed in this direction for a compre-hensive understanding. One of the principles of all geo-scientific research is that, sufficient details should be provided in any research publication that will allow an independent investigator working in an independent laboratory to replicate and confirm any published mea-surement21. Our reported results here conform to this requirement.

Accuracy, precision and detection limits

The variation for the mean of three separate dissolutions run in duplicate (each element determined six times) is indicated in Tables 4 and 5. Overall, precisions <5% RSD with comparable accuracies were obtained for most

Table 5. Concentration (μg/g) of Pt and Pd in international platinum group element geological reference materials determined by MP-AES after NiS fire assay-Te co-precipitation separation and pre-concentration method

Pt (μg/g) Pd (μg/g)

NiS-ICP-MS NiS-ICP-MS

Sample This study method 18

RV % RSD This study method 18 RV % RSD

WMS-1 1.99 – 1.74 0.54 1.19 – 1.19 1.82

PTC-1A 2.98 – 2.72 ± 0.11 4.32 4.13 – 4.48 0.85

PTM-1 5.83 – 5.8 4.86 8.29 – 8.1 0.44 SARM-7 3.84 3.81 3.74 ± 0.05 2.15 1.64 1.55 1.53 1.26 WPR-1 2.81 2.76 2.85 ± 0.12 0.52 2.41 2.45 2.35 ± 0.09 1.11

PTC-1 2.83 – 3 0.25 12.98 – 12.7 1.16

n = 6; RV, Certified values from GEOREM (http://georem.mpch-mainz.gwdg.de ); –, Not available.

Table 6. Detection limits in solution (ng/ml) for Au, Ag, Pt and Pd by MP-AES in comparison with other well-established contemporary analytical techniques

Detection limits (ng/ml)

MP-AES Analyte Wavelength (nm) (This study) F-AAS 17 GF-AAS 3 ICP-AES 16,24 ICP-MS 18 HR-ICP-MS 25

Au 267.595 1.82 20 0.03 6 0.010 0.0012 Ag 328.068 0.5 10 – 2 0.020 0.028 Pt 265.945 5 100 0.6 30 0.004 0.054 Pd 363.470 1.9 20 0.3 44 0.010 0.00640

determinations. However, precision was highly dependent on the absolute concentration in the material. Determina-tions made close to the MP-AES detection limit gave the poorest precision, as in the case of Ox-9, for example, in Table 4. More consistent results were obtained for ele-ments at relatively higher concentration levels, with many yielding RSDs much better than ± 2%. This range of pre-cisions is expected many times in the determination of Au, Ag, Pt and Pd, because of the heterogeneity effects in their distribution in natural materials and also due to pos-sible insufficient recoveries of Pt and Pd in the NiS bead and the follow-up solution chemistry procedure.

In general, determination of precious metals in geo-logical samples is a challenging task because of the extremely low concentration levels (ng/g or pg/g) of these elements, varied and complex geological matrices and their heterogeneous distribution. Extremely sensitive ana-lytical techniques, which can offer very low limits of detection (LODs), are required to detect and accurately determine these elements in a variety of geological mate-rials. LODs are a measure of instrument performance. Comparative detection limits are presented in Table 6. Undoubtedly, high-resolution ICP-MS (HR-ICP-MS) is the most sensitive analytical technique available today. The detection limits for all precious metals studied by MP-AES here are found to be in the 0.5–5 ng/ml range. During the last four decades, AAS was the leading ana-lytical technique, especially for Au and to a lesser extent for Pt and Pd analysis. The classical lead fire-assay col-lection technique in association with F-AAS is normally the method used to determine these elements for the evaluation of ore-grade material 6,17, but the method can-not offer the required sensitivity for these elements, due to interference effects of PGE with each other. Besides AAS methods, colorimetric and titrimetric methods were also in use during this period. Instrumental neutron acti-vation analysis (INAA) is capable of detecting Au directly in solid samples at ng/g levels, but is not sensi-tive enough for similar measurements of Pt and Pd. Though INAA offers very low detection limits, it requires regular access to a nuclear reactor. It is not suitable for routine analysis, but it is particularly useful for checking other methods. Its contribution to the exploration studies is limited because usually it cannot handle large volumes of samples. ICP-AES methods are also characterized by lower sensitivity and prone to interference effects, parti-cularly from transition metal lines for the determination of precious metals in geological materials. However, these effects can be successfully overcome by the selec-tion of alternative analytical lines and/or adopting matrix separation procedures 22. This technique enabled accurate PGE determinations at relatively higher concentration levels in geological materials. However, during the last three decades, INAA, GF-AAS and ICP-MS have proved to be sufficiently sensitive for the determination of noble metals at geochemical background levels. In general, methods based on GF-AAS, ICP-AES, INAA and ICP-MS have proved to be reliable and efficient for the de-

termination of ng/g–μg/g level concentrations of precious metals as a matter of routine on the very large number of samples collected during any exploration programme. The present study proves that the MP-AES technique pos-sesses the required sensitivity together with accuracy for the analysis of rock and ore samples in precious metal exploration studies. This technique also compares favourably with other well-proven techniques such as F-AAS, GF-AAS and ICP-AES for the determination of precious metals because it offers the required sensitivity, minimal interferences and is also simple and relatively inexpensive.

Conclusion

This study considers the importance of choosing proper sample decomposition, separation and pre-concentration methods before the application of an instrumental ana-lytical technique for the detection and determination of Au, Ag, Pt and Pd in rock and ore samples. MP-AES is relatively a new analytical technique; the commercial instruments were released only in 2011. This study of precise determination of Au, Ag, Pt and Pd at sub-μg/g levels in rock and ore materials (ng/ml in sample solu-tions) at the required accuracy and precision levels dem-onstrates the potential of this technique for precious metal exploration studies. Matrix effects were found to be minimal in the determination of Au and Ag in rocks and ore samples by the MP-AES technique. Also, the results obtained by MP-AES in this study compared well with those of the established techniques such as F-AAS and ICP-MS. Since the instrument uses a microwave-induced nitrogen plasma as an excitation source, running costs are significantly reduced as only nitrogen is required for plasma operation. This instrument also offers low-cost elemental analysis with improved laboratory safety as no gas cylinders are required as a nitrogen generator with air compressor can be used instead of a nitrogen cylinder for generating the nitrogen plasma. MP-AES is an ideal in-strumental analytical technique for any elemental analysis in the laboratory, especially in remote sites and mobile laboratories where regular supply of different gases such as acetylene, nitrous oxide and argon is expensive and problematic, particularly in remote areas. Finally, this study reveals that MP-AES is a good addition to the already existing array of established analytical techniques for an analytical chemistry laboratory. Compared to flame AAS, this technique provides improved linear dynamic range, superior detection limits and fast sequen-tial measurement. Using the sample preparation proce-dures described in this study and MP-AES, a large number of rock and ore samples can be analysed easily and quickly in a limited time required in any precious metal exploration programme. Further detailed studies in this direction, particularly the inter-elemental interference and other matrix effects are necessary to understand the complete potential of this technique.

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M., Gnaneswara Rao, T. and Dasaram, B., Determination of the

platinum-group elements and gold in manganese nodule reference samples by nickel sulphide fire-assay and Te co-precipitation with ICP-MS. Indian J. Mar. Sci ., 2006, 35, 7–16.

19. Twyman, R. M., Atomic Emission Spectrometry , Elsevier, 2005, pp. 190–198.

20.

Balaram, V. et al., A rapid method for the determination of gold in rocks, ores and other geological materials by F-AAS and GF-AAS after separation and preconcentration by DIBK extraction for prospecting studies. MAPAN – J. Metrol. Soc. India , 2012, 27, 87–95.

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Potts, P. J., A proposal for the publication of geochemical data in the scientific literature. Geostand. Geoanal. Res ., 2012, 6, 225–230.

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Bencs, L., Ravindra, K. and Grieken, R. V., Methods for the determination of platinum group elements originating from the abrasion of automotive catalytic converters. Spectrochim. Acta Part B , 2003, 58, 1723–1755. 23. Balaram, V. et al., Preparation and certification of high-grade gold

geochemical reference material. Accredit. Qual. Assur ., 2006, 11, 329–335.

24. Montaser, A. and Golightly, D. W. (eds), Inductively Coupled

Plasma in Analytical Atomic Spectrometry , VCH Publishers, New York, 1987.

25. Yamasaki, S., Tsumura, A. and Takaku, Y., Ultra-trace element in

terrestrial water as determined by high resolution ICP-MS. Micro-chem. J ., 1994, 49, 305–318.

ACKNOWLEDGEMENTS. We thank CSIR–National Geophysical Research Institute, Hyderabad, for providing funds and permission to publish this work. P.R. thanks DST, New Delhi, for financial assistance through INSPIRE Faculty Award and K.A. thanks UGC, New Delhi for financial support in the form of BSR Faculty Fellowship.

Received 26 December 2012; revised accepted 29 January 2013

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英语中的比较级与最高级 详解

比较级与最高级 1.as...as 与(not) as(so)...as as...as...句型中，as的词性 第一个as是副词，用在形容词和副词的原级前，常译为“同样地”。第二个as是连词，连接与前面句子结构相同的一个句子(相同部分常省略)，可译为“同..... He is as tall as his brother is (tall) . (后面的as 为连词) 只有在否定句中，第一个as才可换为so 改错: He is so tall as his brother.（X） 2.在比较状语从句中，主句和从句的句式结构一般是相同的 与as...as 句式中第二个as一样，than 也是连词。as和than这两个连词后面的从句的结构与前面的句子大部分情况下结构是相同的，相同部分可以省略。 He picked more apples than she did. 完整的表达为: He picked more apples than she picked apples. 后而的picked apples和前面相同，用did 替代。 He walked as slowly as she did.完整表达为: He walked as slowly as she walked slowly. she后面walked slowly与前面相同，用did替代。

3.谓语的替代 在as和than 引导的比较状语从句中，由于句式同前面 主句相同，为避免重复，常把主句中出现而从句中又出现的动词用do的适当形式来代替。 John speaks German as fluently as Mary does. 4.前后的比较对象应一致 不管后面连词是than 还是as,前后的比较对象应一致。The weather of Beijing is colder than Guangzhou. x than前面比较对象是“天气”，than 后面比较对象是“广州”，不能相比较。应改为: The weather of Bejing is colder than that of Guangzhou. 再如: His handwriting is as good as me. 应改为: His handwriting is as good as mine. 5.可以修饰比较级的词 常用来修饰比较级的词或短语有: Much,even,far,a little,a lot,a bit,by far,rather,any,still,a great deal等。 by far的用法: 用于强调，意为“...得多”“最最...”“显然”等，可修饰形容词或副词的比较级和最高级，通常置于其后，但是若比较级或最高级前有冠词，则可置于其前或其后。

The way常见用法

The way 的用法 Ⅰ常见用法： 1)the way+ that 2)the way + in which（最为正式的用法） 3)the way + 省略（最为自然的用法） 举例：I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法： 在当代美国英语中，the way用作为副词的对格，“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2）The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3）The way =how/ how much No one can imagine the way he missed her. 4）The way =because

人教版(新目标)初中英语形容词与副词的比较级与最高级

人教版（新目标）初中英语形容词与副词的比较级与最高级 （一）规则变化： 1．绝大多数的单音节和少数双音节词，加词尾-er ，-est tall—taller—tallest 2．以不发音的e结尾的单音节词和少数以-le结尾的双音节词只加-r，-st nice—nicer—nicest , able—abler—ablest 3．以一个辅音字母结尾的重读闭音节词或少数双音节词，双写结尾的辅音字母，再加-er，-est big—bigger—biggest 4．以辅音字母加y结尾的双音节词，改y为i再加-er，-est easy—easier—easiest 5．少数以-er，-ow结尾的双音节词末尾加-er，-est clever—cleverer—cleverest, narrow—narrower—narrowest 6．其他双音节词和多音节词，在前面加more，most来构成比较级和最高级 easily—more easily—most easily （二）不规则变化 常见的有： good / well—better—best ; bad (ly)/ ill—worse—worst ; old—older/elder—oldest/eldest many / much—more—most ; little—less—least ; far—farther/further—farthest/furthest

用法： 1．原级比较：as + adj./adv. +as（否定为not so/as + adj./adv. +as）当as… as中间有名字时，采用as + adj. + a + n.或as + many / much + n. This is as good an example as the other is . I can carry as much paper as you can. 表示倍数的词或其他程度副词做修饰语时放在as的前面 This room is twice as big as that one. 倍数+as+adj.+as = 倍数+the +n.+of Your room is twice as larger as mine. = Your room is twice the size of mine. 2．比较级+ than 比较级前可加程度状语much, still, even, far, a lot, a little, three years. five times,20%等 He is three years older than I (am). 表示“（两个中）较……的那个”时，比较级前常加the（后面有名字时前面才能加冠词） He is the taller of the two brothers. / He is taller than his two brothers. Which is larger, Canada or Australia? / Which is the larger country, Canada or Australia? 可用比较级形式表示最高级概念，关键是要用或或否定词等把一事物（或人）与其他同类事物（或人）相分离 He is taller than any other boy / anybody else.

英语中的比较级和最高级

大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基础上变化的。分为规则变化和不规则变化。 规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加 -er 和 -est 构成。 great (原级) (比较级) (最高级) 2) 以 -e 结尾的单音节形容词的比较级和最高级是在词尾加 -r 和 -st 构成。wide (原级) (比较级) (最高级) 3)少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和 -est 构成。 clever(原级) (比较级) (最高级) 4) 以 -y 结尾,但 -y 前是辅音字母的形容词的比较级和最高级是把 -y 去掉,加上 -ier 和-est 构成. happy (原形) (比较级) (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该辅音字母然后再加 -er和-est。 big (原级) (比较级) (最高级) 6) 双音节和多音节形容词的比较级和最高级需用more 和 most 加在形容词前面来构成。 beautiful (原级) (比较级) (比较级) difficult (原级) (最高级) (最高级) 常用的不规则变化的形容词的比较级和最高级: 原级------比较级------最高级 good------better------best many------more------most much------more------most bad------worse------worst far------farther, further------farthest, furthest 形容词前如加 less 和 least 则表示"较不"和"最不 形容词比较级的用法: 形容词的比较级用于两个人或事物的比较,其结构形式如下: 主语+谓语(系动词)+ 形容词比较级+than+ 对比成分。也就是, 含有形容词比较级的主句+than+从句。注意从句常常省去意义上和主句相同的部分, 而只剩下对比的成分。

The way的用法及其含义(二)

The way的用法及其含义（二） 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语： 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势，忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中

英语比较级和最高级的用法归纳

英语比较级和最高级的用法归纳 在学习英语过程中，会遇到很多的语法问题，比如比较级和最高级的用法，对于 这些语法你能够掌握吗？下面是小编整理的英语比较级和最高级的用法，欢迎阅读！ 英语比较级和最高级的用法 一、形容词、副词的比较级和最高级的构成规则 1.一般单音节词和少数以-er，-ow结尾的双音节词，比较级在后面加-er，最高级 在后面加-est; (1)单音节词 如：small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest (2)双音节词 如：clever→cleverer→cleverest narrow→narrower→narrowest 2.以不发音e结尾的单音节词，比较在原级后加-r，最高级在原级后加-st; 如：large→larger→largest nice→nicer→nicest able→abler→ablest 3.在重读闭音节(即：辅音+元音+辅音)中，先双写末尾的辅音字母，比较级加-er，最高级加-est; 如：big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4.以“辅音字母+y”结尾的双音节词，把y改为i，比较级加-er，最高级加-est; 如：easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5.其他双音节词和多音节词，比较级在前面加more，最高级在前面加most; 如：bea utiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily 注意：(1)形容词最高级前通常必须用定冠词 the，副词最高级前可不用。 例句： The Sahara is the biggest desert in the world. (2) 形容词most前面没有the，不表示最高级的含义，只表示"非常"。 It is a most important problem. =It is a very important problem.

(完整版)the的用法

定冠词the的用法： 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...

英语比较级和最高级的用法

More than的用法 A. “More than+名词”表示“不仅仅是” 1)Modern science is more than a large amount of information. 2)Jason is more than a lecturer; he is a writer, too. 3) We need more than material wealth to build our country.建设我们国家，不仅仅需要物质财富. B. “More than+数词”含“以上”或“不止”之意，如： 4)I have known David for more than 20 years. 5)Let's carry out the test with more than the sample copy. 6) More than one person has made this suggestion. 不止一人提过这个建议. C. “More than+形容词”等于“很”或“非常”的意思，如： 7)In doing scientific experiments, one must be more than careful with the instruments. 8)I assure you I am more than glad to help you. D. more than + (that)从句，其基本意义是“超过（=over）”，但可译成“简直不”“远非”.难以，完全不能（其后通常连用情态动词can） 9) That is more than I can understand . 那非我所能懂的. 10) That is more than I can tell. 那事我实在不明白。 11) The heat there was more than he could stand. 那儿的炎热程度是他所不能忍受的 此外，“more than”也在一些惯用语中出现，如： more...than 的用法 1. 比……多，比……更 He has more books than me. 他的书比我多。 He is more careful than the others. 他比其他人更仔细。 2. 与其……不如 He is more lucky than clever. 与其说他聪明，不如说他幸运。 He is more （a）scholar than （a）teacher. 与其说他是位教师，不如说他是位学者。 注：该句型主要用于同一个人或物在两个不同性质或特征等方面的比较，其中的比较级必须用加more 的形式，不能用加词尾-er 的形式。 No more than/not more than 1. no more than 的意思是“仅仅”“只有”“最多不超过”，强调少。如： --This test takes no more than thirty minutes. 这个测验只要30分钟。 --The pub was no more than half full. 该酒吧的上座率最多不超过五成。-For thirty years，he had done no more than he （had）needed to. 30年来，他只干了他需要干的工作。 2. not more than 为more than （多于）的否定式，其意为“不多于”“不超过”。如：Not more than 10 guests came to her birthday party. 来参加她的生日宴会的客人不超过十人。 比较： She has no more than three hats. 她只有3顶帽子。（太少了） She has not more than three hats. 她至多有3顶帽子。（也许不到3顶帽子） I have no more than five yuan in my pocket. 我口袋里的钱最多不过5元。（言其少） I have not more than five yuan in my pocket. 我口袋里的钱不多于5元。（也许不到5元） more than, less than 的用法 1. （指数量）不到，不足 It’s less than half an hour’s drive from here. 开车到那里不到半个钟头。 In less than an hour he finished the work. 没要上一个小时，他就完成了工作。 2. 比……（小）少 She eats less than she should. 她吃得比她应该吃的少。 Half the group felt they spent less than average. 半数人觉得他们的花费低于平均水平。 more…than,/no more than/not more than (1)Mr．Li is ________ a professor; he is also a famous scientist． (2)As I had ________ five dollars with me, I couldn’t afford the new jacket then． (3)He had to work at the age of ________ twelve． (4)There were ________ ten chairs in the room．However, the number of the children is twelve． (5)If you tel l your father what you’ve done, he’ll be ________ angry． (6)－What did you think of this novel? －I was disappointed to find it ________ interesting ________ that one． 倍数表达法 1. “倍数+形容词（或副词）的比较级+than+从句”表示“A比B大（长、高、宽等）多少倍” This rope is twice longer than that one.这根绳是那根绳的三倍（比那根绳长两倍）。The car runs twice faster than that truck.这辆小车的速度比那辆卡车快两倍（是那辆卡车的三倍）。 2. “倍数+as+形容词或副词的原级+as+从句”表示“A正好是B的多少倍”。

“the way+从句”结构的意义及用法

“tｈｅwａｙ+从句”结构的意义及用法 首先让我们来看下面这个句子: Ｒead the foｌloｗｉnｇpassagｅａnd talkａbout ｉt wi ｔh your classmaｔes．Try tｏｔeｌl whaｔyｏu thiｎk ｏf Tom aｎd ｏｆｔhe ｗay the chiｌｄrenｔrｅated ｈim. 在这个句子中，ｔhe waｙ是先行词,后面是省略了关系副词that或in whｉch的定语从句。 下面我们将叙述“the ｗaｙ+从句”结构的用法。 1.tｈe wａy之后，引导定语从句的关系词是tｈat而不是hoｗ,因此，<<现代英语惯用法词典＞＞中所给出的下面两个句子是错误的：Ｔhｉs is ｔｈeｗayｈowｉtｈａppened. This is the way how he ａlwａｙs treats me. 2．在正式语体中,thaｔ可被in which所代替;在非正式语体中，ｔhat则往往省略。由此我们得到theｗay后接定语从句时的三种模式：1) tｈe ｗaｙ＋ｔhａt-从句２）the way +ｉn whiｃh－从句3) the ｗay +从句 例如：Ｔｈe way(in whiｃh ，thａt) ｔhｅｓｅｃomｒade ｓloｏｋａｔｐrobｌems is wrong．这些同志看问题的方法

不对。 Ｔｈｅｗａy(that ,ｉn ｗhiｃh)yoｕ’ｒe doinｇit is comple ｔeｌy crａzy.你这么个干法,简直发疯。 Wｅａdmiｒｅd him for thｅｗay ｉｎｗhｉch he fａｃeｓdiｆficultieｓ． Waｌlａｃe ａｎd Ｄarwiｎｇreed ｏn the way ｉｎwhi ｃh ｄｉfｆｅrｅnt forms ｏf life had ｂegｕn.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 Thｉs is ｔｈe ｗaｙ（tｈａｔ) hｅdｉd it. I lｉkeｄｔhe waｙ(ｔhat) ｓｈeｏｒganized ｔhe ｍeetｉng． 3.theｗay(tｈat)有时可以与hｏw(作“如何”解）通用。例如： That’s tｈe ｗaｙ(tｈaｔ) shｅspoke. = Tｈat’s how shｅspoke.

初中英语比较级和最高级讲解与练习

初中英语比较级和最高级讲解与练习 形容词比较级和最高级 一．绝大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 1. 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 2. 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基 础上变化的。分为规则变化和不规则变化。 二．形容词比较级和最高级规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加-er 和-est 构成。 great (原级) greater(比较级) greatest(最高级) 2) 以-e 结尾的单音节形容词的比较级和最高级是在词尾加-r 和-st 构成。 wide (原级) wider (比较级) widest (最高级) 3) 少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和-est构成。 clever(原级) cleverer(比较级) cleverest(最高级)， slow(原级) slower(比较级) slowest (最高级) 4) 以-y 结尾,但-y 前是辅音字母的形容词的比较级和最高级是把-y 去掉,加上-ier 和-est 构成. happy (原形) happier (比较级) happiest (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该 辅音字母然后再加-er和-est。 原形比较级最高级原形比较级最高级 big bigger biggest hot hotter hottest red redder reddest thin thinner thinnest 6) 双音节和多音节形容词的比较级和最高级需用more 和most 加在形容词前面来构 成。 原形比较级最高级 careful careful more careful most careful difficult more difficult most difficult delicious more delicious most delicious 7)常用的不规则变化的形容词的比较级和最高级: 原级比较级最高级 good better best 好的 well better best 身体好的 bad worse worst 坏的 ill worse worst 病的 many more most 许多 much more most 许多 few less least 少数几个 little less least 少数一点儿 （little littler littlest 小的） far further furthest 远（指更进一步，深度。亦可指更远） far farther farthest 远（指更远，路程）

way 用法

表示“方式”、“方法”，注意以下用法： 1.表示用某种方法或按某种方式，通常用介词in(此介词有时可省略)。如： Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法，其后可接不定式或of doing sth。 如： It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词)，也可跟由that 或in which 引导的定语从句，但是其后的从句不能由how 来引导。如： 我不喜欢他说话的态度。 正：I don’t like the way he spoke. 正：I don’t like the way that he spoke. 正：I don’t like the way in which he spoke. 误：I don’t like the way how he spoke. 4.注意以下各句the way 的用法： That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看，你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题： ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A，而不选其他几项，则要弄清选项中含way的四个短语的不同意义和用法，下面我们就对此作一归纳和小结。 一、in a way的用法 表示：在一定程度上，从某方面说。如： In a way he was right.在某种程度上他是对的。注：in a way也可说成in one way。 二、on the way的用法 1、表示：即将来(去)，就要来(去)。如： Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示：在路上，在行进中。如： He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示：(婴儿)尚未出生。如： She has two children with another one on the way.她有两个孩子，现在还怀着一个。 She's got five children，and another one is on the way.她已经有5个孩子了，另一个又快生了。 三、by the way的用法

英语比较级和最高级

形容词比较级和最高级的形式 一、形容词比较级和最高级的构成 形容词的比较级和最高级变化形式规则如下 构成法原级比较级最高级 ①一般单音节词末尾加 er 和 est strong stronger strongest ②单音节词如果以 e结尾，只加 r 和 st strange stranger strangest ③闭音节单音节词如末尾只有一个辅音字母， 须先双写这个辅音字母，再加 er和 est sad big hot sadder bigger hotter saddest biggest hottest ④少数以 y, er(或 ure), ow, ble结尾的双音节词， 末尾加 er和 est(以 y结尾的词，如 y前是辅音字母， 把y变成i，再加 er和 est，以 e结尾的词仍 只加 r和 st) angry Clever Narrow Noble angrier Cleverer narrower nobler angriest cleverest narrowest noblest ⑤其他双音节和多音节词都在前面加单词more和most different more different most different 1) The most high 〔A〕mountain in 〔B〕the world is Mount Everest，which is situated 〔C〕in Nepal and is twenty nine thousand one hundred and fourty one feet high 〔D〕 . 2) This house is spaciouser 〔A〕than that 〔B〕white 〔C〕one I bought in Rapid City，South Dakota 〔D〕last year. 3) Research in the social 〔A〕sciences often proves difficulter 〔B〕than similar 〔C〕work in the physical 〔D〕sciences. 二、形容词比较级或最高级的特殊形式：

高中英语的比较级和最高级用法总结

比较级和最高级 1.在形容词词尾加上―er‖ ―est‖ 构成比较级、最高级： bright（明亮的）—brighter—brightest broad（广阔的）—broader—broadest cheap（便宜的）—cheaper—cheapest clean（干净的）—cleaner—cleanest clever（聪明的）—cleverer—cleverest cold（寒冷的）—colder—coldest cool（凉的）—cooler—coolest dark（黑暗的）—darker—darkest dear（贵的）—dearer—dearest deep（深的）—deeper—deepest fast（迅速的）—faster—fastest few（少的）—fewer—fewest great（伟大的）—greater—greatest hard（困难的,硬的）—harder—hardest high（高的）—higher—highest kind（善良的）—kinder—kindest light（轻的）—lighter—lightest long（长的）—longer—longest loud（响亮的）—louder—loudest low（低的）—lower—lowest near（近的）—nearer—nearest new（新的）—newer—newest poor（穷的）—poorer—poorest quick（快的）—quicker—quickest quiet（安静的）—quieter—quietest rich（富裕的）—richer—richest short（短的）—shorter—shortest slow（慢的）—slower—slowest small（小的）—smaller—smallest smart（聪明的）—smarter—smartest soft（柔软的）—softer—softest strong（强壮的）—stronger—strongest sweet（甜的）—sweeter—sweetest tall（高的）-taller-tallest thick（厚的）—thicker—thickest warm（温暖的）—warmer—warmest weak（弱的）—weaker—weakest young（年轻的）—younger—youngest 2.双写最后一个字母,再加上―er‖ ―est‖构成比较级、最高级： big（大的）—bigger—biggest fat（胖的）—fatter—fattest hot（热的）—hotter—hottest red（红的）—redder—reddest sad（伤心的）—sadder—saddest thin（瘦的）—thinner—thinnest wet（湿的）—wetter—wettest mad（疯的）—madder—maddest 3.以不发音的字母e结尾的形容词,加上―r‖ ―st‖ 构成比较级、最高级：able（能干的）—abler—ablest brave（勇敢的）—braver—bravest close（接近的）—closer—closest fine（好的,完美的）—finer—finest large（巨大的）—larger—largest late（迟的）—later—latest nice（好的）—nicer—nicest ripe（成熟的）—riper—ripest

The way的用法及其含义(一)

The way的用法及其含义（一） 有这样一个句子：In 1770 the room was completed the way she wanted. 1770年，这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么？其意义如何？在阅读时，学生经常会碰到一些含有the way 的句子，如：No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中，the way之后的部分都是定语从句。第一句的意思是，“没人知道他是怎样发明这台机器的。”the way的意思相当于how；第二句的意思是，“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中，the way也是as的含义。随着现代英语的发展，the way的用法已越来越普遍了。下面，我们从the way的语法作用和意义等方面做一考查和分析： 一、the way作先行词，后接定语从句 以下3种表达都是正确的。例如：“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如：“火灾如何发生的，有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.

(完整版)初中英语比较级和最高级的用法

英语语法---比较级和最高级的用法 在英语中通常用下列方式表示的词:在形容词或副词前加more(如 more natural,more clearly )或加后缀 -er(newer,sooner )。典型的是指形容词或副词所表示的质、量或关系的增加。英语句子中，将比较两个主体的方法叫做“比较句型”。其中，像“A比B更……”的表达方式称为比较级；而“A最……”的表达方式则称为最高级。组成句子的方式是将形容词或副词变化成比较级或最高级的形态。 一、形容词、副词的比较级和最高级的构成规则 1．一般单音节词和少数以-er，-ow结尾的双音节词，比较级在后面加-er，最高级在后面加-est； （1）单音节词 如：small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest （2）双音节词 如：clever→cleverer→cleverest narrow→narrower→narrowest 2．以不发音e结尾的单音节词，比较在原级后加-r，最高级在原级后加-st； 如：large→larger→largest nice→nicer→nicest able→abler→ablest 3．在重读闭音节（即：辅音＋元音＋辅音）中，先双写末尾的辅音字母，比较级加-er，最高级加-est； 如：big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4．以“辅音字母＋y”结尾的双音节词，把y改为i，比较级加-er，最高级加-est； 如：easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5．其他双音节词和多音节词，比较级在前面加more，最高级在前面加most； 如：beautiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily