Betacyanins in fruits from red-purple pitaya

Analytical,Nutritional and Clinical Methods Section

Betacyanins in fruits from red-purple pitaya,Hylocereus polyrhizus

(Weber)Britton &Rose

Florian C.Stintzing,Andreas Schieber,Reinhold Carle*

Institute of Food Technology,Section Plant Foodstu?Technology,Hohenheim University,Garbenstrasse 25,D-70599Stuttgart,Germany

Received 15May 2001;received in revised form 7September 2001;accepted 7September 2001

Abstract

The betalain pattern of Hylocereus polyrhizus (Weber)Britton &Rose is reported for the ?rst time and a highly practicable technique is described for the simultaneous isolation of pigment and mucilage from the mesocarp by extraction with water.Whereas betaxanthins were totally absent,10betacyanins could be separated by HPLC-PDA.For eight betacyanins the respective molecular masses could be obtained by positive ion electrospray mass spectrometry.Five of them were unequivocally assigned to bougainvillein-r-I,betanin,isobetanin,phyllocactin,and iso-phyllocactin.The remaining betacyanins were tentatively identi?ed as (60-O -3-hydroxy-3-methyl-glutaryl)-betanin,its C 15-stereoisomer,and (60-O -3-hydroxy-3–butyryl)-betanin,https://www.wendangku.net/doc/e91203003.html,ing the b -glucosidase assay,acylated structures could be distinguished from non-acylated betacyanins.Contrary to white-?eshed Hylocer-eus undatus (Haworth)Britton &Rose with a slightly pink mesocarp,H.polyrhizus most likely possesses the same set of betalain forming enzymes in both pulp and mesocarp as the betacyanin pattern was found to be similar.#2002Elsevier Science Ltd.All rights reserved.

Keywords:Pitaya;Hylocereus polyrhizus ;Betalain pigments;Natural food colorants

1.Introduction

Oblong shaped fruits of the genus Hylocereus (Berger)Britton &Rose originating from Latin America and known as red pitaya derive from climbing epiphytes belonging to the Cactaceae family.Due to Crassulacean Acid Metabolism (CAM),members of this family exhi-bit an extraordinarily high water-use e?ciency with low water requirements (Raveh,Nerd,&Mizrahi,1998;Winter &Smith,1996).An additional ecological feature was very recently pointed out with CAM plants responding to high CO 2atmospheric concentrations by increasing their biomass production (Drennan &Nobel,2000).Compared to the more common cactus pear (Opuntia sp.),the usually red peel from Hylocereus pos-sesses large scales instead of spines and its pulp only contains small digestible seeds (Raveh,Weiss,Nerd,&Mizrahi,1993).Due to self-incompatibility,cross-polli-nation is required and hand-pollination is still necessary to obtain fruits (Lichtenzveig,Abbo,Nerd,Tel-Zur,&

Mizrahi,2000;Mizrahi &Nerd,1999;Weiss,Nerd,&Mizrahi,1994).Pulp colour in Hylocereus fruits varies from white to red and purple (Nerd,Gutman,&Miz-rahi,1999).Producing a deep purple-coloured ?esh comparable to red beet (Stintzing,Schieber,&Carle,2000b)or amaranth (Cai,Sun,&Corke,1998),fruits from Hylocereus polyrhizus are highly appealing.Public concern about possible or proven harmful e?ects of arti?cial food colorants has increased the search for natural colour sources.Showing a stable appearance in the pH range from 3to 7,betalains have a great poten-tial in colouring a broad array of food.In this view,betacyanins from H.polyrhizus are most promising,not only as colouring agents but also in possessing anti-radical potential (Escribano,Pedren o,Garc?a-Car-mona,&Mun oz,1998;Pedren o &Escribano,2001).Very recently,ripening and postharvest behaviour of Hylocereus undatus (Haworth)Britton &Rose and H.polyrhizus were studied to determine the optimum date of harvest in relation to colour development of pulp and peel (Nerd et al.,1999).However,no data were given about the pigment pattern of H.polyrhizus .Both the juice from the pulp and the aqueous extract of the deep-coloured mesocarp provide a hitherto little known

0308-8146/02/$-see front matter #2002Elsevier Science Ltd.All rights reserved.P I I :S 0308-8146(01)00374-

*Corresponding author.Tel.:+49-711-459-2314;fax:+49-711-459-4110.

E-mail address:carle@uni-hohenheim.de (R.Carle).

source of a natural food colorant.Peel and mesocarp could be exploited for the recovery of a natural thick-ening agent which has yet to be characterized.Muci-lages in the pulp may display similar properties as recently reviewed for Opuntia sp.(Stintzing,Schieber,& Carle,2001).Therefore,the aim of the present work was to develop a method for gaining both pigments and mucilages and thereby getting an insight in the betalain pattern of H.polyrhizus pulp and mesocarp.

2.Materials and methods

2.1.Plant material

Fruits were purchased from Israel and stored at à26 C.After thawing at4 C,they were manually squeezed,and the?ltered juice was?ushed with nitro-gen and kept atà80 C.The mesocarp was removed from the pulp with a stainless steel knife and either stored frozen(à80 C)or taken for analysis.

2.2.Solvents and reagents

Reagents and solvents were purchased from Merck (Darmstadt,Germany)and were of analytical or HPLC grade.C18-Reversed phase cartridges Chromabond 1000mg were from Macherey&Nagel(Du ren,Ger-many). -Glucosidase from sweet almonds was obtained from Serva(Heidelberg,Germany).

2.3.Extraction of mesocarp for pigment recovery

Ten millilitres of puri?ed water were added per1g of plant tissue and macerated in a blender at low speed under ice-cooling.Extraction of the pigments was accomplished within a few minutes.Mucilagenous material was separated from the extract on a Buchner funnel to give a coloured solution.The residue was re-extracted with water and the?ltrate concentrated in vacuo at30 C.Two millilitres of96%EtOH were added to1ml of coloured solution for precipitation of the pectic substances.After separation of the pigment solution with a Buchner funnel,the?lter residue was washed with EtOH/water(2/1,v/v)until all betacyanins were removed.The coloured solution was again con-centrated under reduced pressure and the procedure repeated two times until no further precipitation by addition of EtOH was observed.

2.4.Precipitation of pectic substances and proteins from juice

For removal of pectic and other colloidal substances, 2ml of96%EtOH were added to1ml of sample.After 20min,the mucilages were separated from the aqueous phase and washed with an EtOH/water mixture of2/1 (v/v)until the solid was colourless.EtOH was removed under reduced pressure at30 C to restore the initial sample volume.

2.5.Puri?cation and concentration of betacyanins Desalting was carried out using C18-reversed phase cartridges.Acidi?ed water was prepared by adding TFA to puri?ed water until a pH of2or3was reached, respectively.The sorbent material was activated with three volumes of MeOH,and then rinsed with three volumes of acidi?ed water(pH3).The unpuri?ed sam-ple was adjusted to pH3by addition of0.1N HCl and subsequently applied to the sorbent.The betacyanins non-ionically bound to the material were then desalted by eluting sugars and acids with three volumes of acidi-?ed water(pH3).Elution of the betacyanins was accomplished by addition of acidi?ed MeOH(95/5 MeOH/pH2water,v/v).The desalted sample was repetitively concentrated in vacuo at30 C and resus-pended in water until a pH of5–6was reached.For HPLC analysis,the resulting pigments were rediluted with puri?ed water.

2.6. -Glucosidase assay

The b-glucosidase assay was modi?ed according to Piattelli and Minale(1964).The acetate bu?er(1l)was prepared by dissolving3.95g of sodium acetate in pur-i?ed water,before adding3.0g of glacial acetic acid as well as20ml of1N NaOH and was?nally adjusted to pH5(Wilcox,Wyler,Mabry,&Dreiding,1965).To a mixture of750m l of acetate bu?er50m l of pressed juice were added.An aliquot of this blank solution was applied to the HPLC and the enzymatic hydrolysis started through the addition of200m l of b-glucosidase solution containing83.5units/ml when the?rst peak of the blank eluted on the HPLC-system.Every60min an aliquot of the reaction mixture was injected and the hydrolysis of the betacyanins was monitored over a total period of12h and compared to a blank solution.

2.7.HPLC analysis

2.7.1.System I

The HPLC-system(Hewlett-Packard Series1100, Hewlett Packard,Waldbronn,Germany)was as fol-lows:a thermoautosampler ALS G1313A,a binary gradient pump G1311A,a degasser G1322A,a column oven ColComp G1316A keeping a constant temperature of25 C,and a diode array detection system G1315A. Chromatographic analysis was performed using an analytical scale(250?4.6mm i.d.)AQUA C18-reversed phase column with a particle size of5m m(Phenomenex, Torrance,CA,USA),?tted with a security guard C18

102 F.C.Stintzing et al./Food Chemistry77(2002)101–106

ODS(4?3.0mm i.d.).The mobile phase A consisted of 2%(v/v)acetic acid in water,0.5%acetic acid in water and acetonitrile(50/50,v/v)was used as B.The elution was carried out following a linear gradient from10%B in A to27%B in A in30min.Simultaneous monitoring was performed at320nm for hydroxycinnamoyl moi-eties,at475nm for betaxanthins and at538nm for betacyanins at a?ow rate of1ml/min.

2.7.2.System II

The HPLC-system(Merck,Darmstadt,Germany) was equipped with an auto sampler L-7200,an interface module D-7000,a pump L-7100,a column-oven L-7350 with peltier cooling module,and a diode array detector L-7450A.Chromatographic analysis was performed using an analytical scale(250?3mm i.d.)LUNA C18-reversed phase column with a particle size of5m m (Phenomenex,Torrance,CA,USA),?tted with a security guard C18ODS(4?3.0mm i.d.).HPLC condi-tions were as follows:Eluent A consisted of0.2%(v/v) formic acid in water,a mixture of ACN/water(80/20v/ v)was used as eluent B.Separation of all betalains was achieved in30min at25 C and a?ow rate of1ml/min. Starting with5%B in A at0min,a linear gradient was followed to9%B in A at33min.Monitoring of beta-lains was performed at320nm for hydroxycinnamoyl moieties,at475nm for betaxanthins and at538nm for betacyanins.

2.8.LC-MS analysis

The HPLC-system(Hewlett-Packard Series1100, Hewlett Packard,Waldbronn,Germany)was as fol-lows:a thermoautosampler ALS G1313A,a binary gradient pump G1311A,a degasser G1322A,a column oven ColComp G1316A keeping a constant temperature of25 C,and a diode array detection system G1315A. Chromatographic analysis was performed using an analytical scale(250?3mm i.d.)LUNA C18-reversed phase column with a particle size of5m m(Phenomenex, Ascha?enburg,Germany),?tted with a security guard C18ODS(4?3.0mm i.d.).HPLC conditions were as described for system II.The MS-system was a Micro-mass Platform II equipped with a cross?ow interface. The tuning parameters for positive ion electrospray (ES+)were3.50kV for capillary and40eV for cone at

a source temperature of120 C.

3.Results and discussion

Up till now,the betalain pattern of Hylocereus sp.has not been reported.Although H.undatus has been sub-ject to investigations(Barbeau,1990;Rodr?guez-D?az, Ocampo Hurtado,&Casillas Go mez,1995),no data exist about the pigments in H.polyrhizus.HPLC ana-lyses of a puri?ed juice and of aqueous extracts from the mesocarp revealed the presence of at least eight beta-cyanins and the absence of betaxanthins.Removal of both mucilage and sugars prior to pigment analysis turned out to be advantageous.

3.1.Extraction and puri?cation of betacyanins from mesocarp tissue

For distinction of pigments in the pulp and mesocarp, a method reported by Rodr?guez-D?az et al.(1995)was optimized.As pigment recovery of mesocarp tissue with 0.5-cm cubes was low due to a limited surface,a di?er-ent treatment was required.In addition,the temperature during extraction(40–50 C)was deleterious to beta-cyanin integrity and would proliferate microbial growth.High shear stress during maceration or the extraction with aqueous MeOH as often described for phytochemical analyses(Strack,Steglich,&Wray, 1993)both resulted in gel formation and subsequent entrappment of the pigments.Aqueous extraction at temperatures below10 C after careful tissue macera-tion allowed total discoloration of the tissue.Further precipitation of the pectic-like substances and re-extraction yielded pigments devoid of mucilagenous material.Betacyanin fractions were subsequently desal-ted on a C18-cartridge.The pigments from the mesocarp and from juice derived from the pulp had an identical HPLC pattern.The identity of individual compounds was con?rmed by their spectral properties as well as by LC-MS studies.

3.2. -Glucosidase assay

The b-glucosidase assay is a sensitive tool for di?er-entiating acylated from non-acylated structures.As described by Minale,Piattelli,de Stefano,and Nicolaus (1966),steric hindrances may a?ect the action of emul-sin:b-glucosidase did not cleave phyllocactin as the malonyl residue bound to the glucose unit hampered the enzymic hydrolysis.In this study,the assay yielded betanidin when compounds(1),(2)and(3)were hydro-lyzed,indicating a glucose moiety attached to the cyclo-Dopa structure of betanidin.Due to the low stability of the aglyca,betanidin and isobetanidin readily degraded after being formed,the latter therefore being not detectable(data not shown).The remaining com-pounds,however,were not a?ected by enzymatic action indicating acylated structures of betanin.

3.3.HPLC-PDA and ion electrospray mass spectrometry

By applying two di?erent HPLC-systems to the ana-lysis of betacyanins from H.polyrhizus,similarity of the chromatographic patterns(System I,Fig.1and System

F.C.Stintzing et al./Food Chemistry77(2002)101–106103

II,Fig.2)was ascertained.However,two minor peaks (8and9;Fig.2)could not be resolved in system I.This was due to coelution with compound(7)resulting in peak tailing and lower peak purity of(7).Consequently, system II was chosen for further investigation with all compounds showing a peak purity greater than99%. The identity of these compounds was con?rmed by HPLC(Fig.2)coupled with electrospray mass spectro-metry in the positive ionization mode yielding the fol-lowing protonated molecular ions[M+H]+:(1)m/z 713,(2)m/z551,(3)m/z551,(4)m/z637,(5)m/z637, (6)m/z695,(7)m/z637and(10)m/z695(Table1).All betacyanins produced a daughter ion at m/z389,corre-sponding to[betanidin+H+].Based on its molecular mass,its sensitivity to b-glucosidase and its retention characteristics,the?rst eluting betacyanin(1)was iden-ti?ed as bougainvillein-r-I.Consistent with data on bou-gainvillein-v(Heuer,Richter,Metzger,Wray,Nimtz,& Strack,1994),it eluted prior to betanin on the reversed phase system due to the presence of a di-glucose moiety. Hitherto,only Piattelli and Imperato(1970a)reported on bougainvillein-r-I in purple bracts of Bougainvillea ‘Mrs.Butt’belonging to the red-violet5-O-b-sophoro-side derivatives of betanidin.In contrast to the violet-red 6-O-b-sophorosides of the bougainvillein-v type from B. glabra showing a bathochromic shift in their visible absorption(Heuer et al.,1994;Piattelli&Imperato, 1970b),the absorption characteristics of bougainvillein-r-I were similar to betanin consistent with the?ndings by Piattelli&Imperato(1970a).Results of co-chroma-tographic studies with authentic standards betanin and isobetanin from red beet were con?rmed by mass spec-trometric data for peaks(2)and(3).The relatively longer retention time and the lack of extended UV absorption compared to betanin,indicated betacyanin structures with aliphatic acyl groups:Betacyanins(4) and(7)corresponded to phyllocactin and its C15-dia-stereoisomer.While the mass spectrometric data for phyllocactin were consistent with those of Kobayashi, Schmidt,Nimtz,Wray,and Schliemann(2000),the absorption maxima in the visible range slightly di?ered. The deviation of3nm may be ascribed to the di?erent pH values of the mobile phases used.All remaining compounds were tentatively identi?ed by their spectral properties and by their molecular masses.Resulting fragments at m/z389indicated betanidin type pigments. The occurrence of‘neo’-compounds which would have produced a daughter ion at m/z387corresponding to neobetanidin(Strack,Engel,&Wray,1987)could therefore be excluded.With respect to the UV absorp-tion,there is strong evidence for an acylation with other than cinnamic acid derivatives since the latter would cause an additional absorption band at310–320nm (Heuer,Wray,Metzger,&Strack,1992).The same

was Fig. 1.HPLC separation of betacyanins from red-purple pitaya,

Hylocereus polyrhizus(538nm,system I;peak assignment is given in

Table

1).

Fig. 2.HPLC separation of betacyanins from red-purple pitaya,

Hylocereus polyrhizus(538nm,system II;peak assignment is given in

Table1).

104 F.C.Stintzing et al./Food Chemistry77(2002)101–106

true for compounds8and9(Fig.2;HPLC-system II) for which no de?nite mass spectrometric data could be obtained.Evidence is given that compounds6and10 are C15-stereoisomers of betanin acylated with3-hydroxy-methyl-glutaric acid.The identical acid was found in iresinin I and its C15-epimer iresinin II which were reported for Iresine herbstii Hook.F.ex Lindl. (Cai,Sun,&Corke,2001;Minale et al.,1966)as well as for Amaranthus species(Cai et al.,2001).Considering its molecular mass and its spectral properties,we assume compound5to be betanidin-5-O-glycoside acylated with3-hydroxy-butyric acid.

Simultaneous occurrence of5-and6-O-glycosides of betanidin in the same plant tissue has been reported in ?owers from Gomphrena globosa L.but was found to be very rare(Heuer et al.,1992).Recent investigations on Phytolacca americana L.(Schliemann et al.,1996)and on the Amaranthaceae(Cai et al.,2001)gave additional proof of this interesting phytochemical phenomenon. Other studies(Heuer et al.,1992;Piattelli&Imperato, 1970a)maintain that the attachment of sugar moieties to the C6-position of betanidin induces a slight bath-ochromic shift in comparison to the corresponding C5-adducts.However,a similar e?ect could not be observed for either of the betacyanins found(Table1), thus indicating the presence of betanidin5-O-glycosides. Both reversed phase systems parallely showed seven distinct peaks with uniform spectral data and a few minor ones,one of which was bougainvillein-r-I.Fur-ther studies are underway to fully elucidate pigments (5),(6),and(10)in H.polyrhizus.

4.Conclusion

This study on the pigment pattern of H.polyrhizus showed that seven major betacyanins with identical l max contribute to its deep-purple colour.Since betaxanthins tend to degrade more easily resulting in a shade of brown colour(Stintzing et al.,2000b),their absence is technologically advantageous.The betalain composition of mesocarp and pulp did not di?er,thus indicating a similar set of enzymes in the two neighbouring tissues. Simple aqueous extraction of the mesocarp did not only yield the betalain pigments but also allowed their com-plete separation from the mucilagenous material at the same time.Considering an economical perspective,H. polyrhizus represents a potential commercial source of betalains,since by-products of fruit manufacture can also be exploited:whereas the pectic-like substance could be used in the food industry as a thickening agent or as a moisturizer in cosmetic products,the aqueous mesocarp extract as well as the juice from the pulp could serve as a colouring stu?for low acid food com-modities.Additionally,betacyanins were very recently recognized as antiradical agents(Escribano et al.,1998; Pedren o&Escribano,2001).Soluble?bres have been associated with blood sugar regulation in humans suf-fering from diabetes mellitus type II(Trejo-Gonza lez et al.,1996).Other studies showed that mucilages may exert a positive in?uence on cholesterol metabolism (Luz-Ferna ndez,Lin,Trejo,&McNamara,1992;Luz-Ferna ndez,Trejo,&McNamara,1990,1994)under-lining the nutritional signi?cance of H.polyrhizus.This again points out the high potential of hitherto little exploited plants as reviewed for the genus Opuntia of the Cactaceae family(Stintzing,Schieber,&Carle, 2000a;Stintzing et al.,2001).

Acknowledgements

The authors thank Dr.W.Armbruster,Institute of Food Chemistry,Hohenheim University,for perform-

Table1

Peak assignment for betacyanin pigments from pulp and mesocarp of Hylocereus polyrhizus(Weber)Britton&Rose

Peak

number a

De?nitive name(trivial name)HPLC-System I HPLC-System II[M+H]+

R t(min)l max VIS

(nm)R t(min)l max VIS

(nm)

1Betanidin-5-O-b-sophoroside(Bougainvillein r-I)9.245329.04536713

2Betanidin-5-O-b-glucoside(Betanin)11.2853611.43536551

3Isobetanidin-5-O-b-glucoside(Isobetanin)14.4753615.59536551

4Betanidin-5-O-(60-O-malonyl)-b-glucoside(Phyllocactin)17.0153620.67536637

7b Iso-betanidin-5-O-(60-O-3-hydroxy-3-methyl-glutaryl)-b-glucoside20.3653625.69536695

6b Betanidin-5-O-(60-O-3-hydroxy-3-methyl-glutaryl)-b-glucoside19.0753624.67536695

10b Betanidin-5-O-(60-O-3-hydroxy-butyryl)-b-glucoside22.1053629.12536637

8Unknown betacyanin–c–c27.70536–c

9Unknown betacyanin–c–c28.57536–c

5Isobetanidin-5-O-(60-O-malonyl)-b-glucoside(Isophyllocactin)18.5253623.27536637

a As indicated in Figs.1and2.

b Tentatively identi?ed betanin-type structures.

c Not detectable.

F.C.Stintzing et al./Food Chemistry77(2002)101–106105

ing LC-MS analyses.The authors are grateful to fruit-International Fruit Foundation,Heidelberg,Germany for?nancial support.

References

Barbeau,G.(1990).La pitahaya rouge,un nouveau fruit exotique. Fruits,45(2),141–147.

Cai,Y.,Sun,M.,&Corke,H.(1998).Colorant properties and stabi-lity of Amaranthus pigments.Journal of Agricultural and Food Chemistry,46(11),4491–4495.

Cai,Y.,Sun,M.,&Corke,H.(2001).Identi?cation and distribution of simple and acylated betacyanins in the Amaranthaceae.Journal of Agricultural and Food Chemistry,49(4),1971–1978.

Drennan,P.M.,&Nobel,P.S.(2000).Responses of CAM species to increasing atmospheric CO2concentrations.Plant,Cell and Envi-ronment,23,767–781.

Escribano,J.,Pedren o,M.A.,Garc?a-Carmona,F.,&Mun oz,R. (1998).Characterization of the antiradical activity of betalains from Beta vulgaris L.roots.Phytochemical Analysis,9,124–127. Heuer,S.,Richter,S.,Metzger,J.W.,Wray,V.,Nimtz,M.,&Strack, D.(1994).Betacyanins from bracts of Bougainvillea glabra.Phyto-chemistry,37(3),761–767.

Heuer,S.,Wray,V.,Metzger,J.W.,&Strack,D.(1992).Betacyanins from?owers of Gomphrena globosa.Phytochemistry,31(5),1801–1807.

Kobayashi,N.,Schmidt,J.,Nimtz,M.,Wray,V.,&Schliemann,W. (2000).Betalains from Christmas cactus.Phytochemistry,54(4), 419–426.

Lichtenzveig,J.,Abbo,S.,Nerd, A.,Tel-Zur,N.,&Mizrahi,Y. (2000).Cytology and mating systems in the climbing cacti Hylocer-eus and Selenicereus.American Journal of Botany,87(7),1058–1065. Luz-Fernandez,M.,Lin,E.C.K.,Trejo,A.,&McNamara,D.J. (1992).Prickly pear(Opuntia sp.)pectin reverses low density lipo-protein receptor suppression induced by a hypercholesterolemic diet in guinea pigs.Journal of Nutrition,122,2330–2340.

Luz-Fernandez,M.,Lin,E.C.K.,Trejo,A.,&McNamara,D.J. (1994).Prickly pear(Opuntia sp.)pectin alters hepatic cholesterol metabolism without a?ecting cholesterol absorption in guinea pigs fed a hypercholesterolemic diet.Journal of Nutrition,124,817–824. Luz-Fernandez,M.,Trejo,A.,&McNamara,D.J.(1990).Pectin isolated from prickly pear(Opuntia sp.)modi?es low density lipo-protein metabolism in cholesterol-fed guinea pigs.Journal of Nutri-tion,120,1283–1290.

Minale,L.,Piattelli,M.,de Stefano,S.,&Nicolaus,R.A.(1966). Pigments of Centrospermae.VI.Acylated Betacyanins.Phytochem-istry,5,1037–1052.

Mizrahi,Y.,&Nerd,A.(1999).Climbing and columnar cacti:new arid land fruit crops.In J.Janick(Ed.),Perspectives on new crops and new uses(pp.358–366).Alexandria,VA:ASHS Press.

Nerd,A.,Gutman,F.,&Mizrahi,Y.(1999).Ripening and post-harvest behaviour of fruits of two Hylocereus species(Cactaceae). Postharvest Biology and Technology,17,39–45.Pedren o,M.A.,&Escribano,J.(2001).Correlation between anti-radical activity and stability of betanine from Beta vulgaris L.roots under di?erent pH,temperature and light conditions.Journal of the Science of Food and Agriculture,81(7),627–631.

Piattelli,M.,&Imperato,F.(1970a).Betacyanins from Bougainvillea. Phytochemistry,9,455–458.

Piattelli,M.,&Imperato,F.(1970b).Pigments of Bougainvillea gla-bra.Phytochemistry,9,2557–2560.

Piattelli,M.,&Minale,L.(1964).Pigments of Centrospermae.I. Betacyanins from Phyllocactus hybridus Hort.and Opuntia?cus-indica Mill.Phytochemistry,3,307–311.

Raveh,E.,Nerd,A.,&Mizrahi,Y.(1998).Responses of two hemi-epiphytic fruit crop cacti to di?erent degrees of shade.Scientia Horticulturae,73,151–164.

Raveh,E.,Weiss,J.,Nerd,A.,&Mizrahi,Y.(1993).Pitayas(Genus Hylocereus):a new fruit crop for the Negev Desert of Israel.In J.Janick,&J.E.Simon(Eds.),New crops(pp.491–495).New York:Wiley.

Rodr?guez-D?az,A.J.,Ocampo Hurtado,A.L.,&Casillas Go mez, F.J.(1995).Extraccio n de un colorante natural a partir de la ca s-cara de la pitahaya(Hylocereus undatus).Tecnolog?′a de Alimentos (Me′xico),30(6),22–26.

Schliemann,W.,Joy,R.W.IV,Komamine, A.,Metzger,J.W., Nimtz,M.,Wray,V.,&Strack,D.(1996).Betacyanins from plants and cell cultures of Phytolacca americana.Phytochemistry,42(4), 1039–1046.

Stintzing,F.C.,Schieber,A.,&Carle,R.(2000a).Cactus pear—a promising component to functional food.Obst-,Gemu¨se-und Kar-to?elverarbeitung,85(1),40–47.

Stintzing,F.C.,Schieber,A.,&Carle,R.(2000b).Rote Bete als fa r-bendes Lebensmittel—eine Bestandsaufnahme.Obst-,Gemu¨se-und Karto?elverarbeitung,85(5/6),196–204.

Stintzing,F.C.,Schieber,A.,&Carle,R.(2001).Phytochemical and nutritional signi?cance of cactus pear.European Food Research and Technology,212(4),396–407.

Strack,D.,Engel,U.,&Wray,V.(1987).Neobetanin:a new natural plant constituent.Phytochemistry,26(8),2399–2400.

Strack,D.,Steglich,W.,&Wray,V.(1993).Betalains.In P.M.Dey, &J.B.Harborne(Eds.),Methods in plant biochemistry8,P.G. Waterman,alkaloids and sulphur compounds(pp.421–450).London: Academic Press.

Trejo-Gonza lez,A.,Gabriel-Ortiz,G.,Puebla-Pe rez,A.M.,Hu?zar-Contreras,M.D.,Mungu?a-Mazariegos,M.R.,Mej?a-Arregu?n,S., &Calva,E.(1996).A puri?ed extract from prickly pear cactus (Opuntia fuliginosa)controls experimentally induced diabetes in rats.Journal of Ethnopharmacology,55,27–33.

Weiss,J.,Nerd,A.,&Mizrahi,Y.(1994).Flowering behavior and pollination requirements in climbing cacti with fruit crop potential. HortScience,29(12),1487–1492.

Wilcox,M.E.,Wyler,H.,Mabry,T.J.,&Dreiding,A.S.(1965).Die Struktur des Betanins-U ber die Konstitution des Randenfarbsto?es Betanin.Helvetica Chimica Acta,48(1),252–258.

Winter,K.,&Smith,J.A.C.(1996).Crassulacean acid metabolism. biochemistry,ecophysiology and evolution(Ecological Studies114). Berlin/Heidelberg/New York:Springer Verlag.

106 F.C.Stintzing et al./Food Chemistry77(2002)101–106

(完整版)介词for用法归纳

介词for用法归纳 用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for? 你干吗这样做？ That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time? 她这次去干什么去了？ He was waiting for the bus. 他在等公共汽车。 【用法说明】在通常情况下，英语不用for doing sth 来表示目的。如： 他去那儿看他叔叔。 误：He went there for seeing his uncle. 正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。(见下面的有关用法) 用法2：(表利益)为，为了。如： What can I do for you? 你想要我什么？ We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me? 请你替我提这个东西好吗？ Do more exercise for the good of your health. 为了健康你要多运动。 【用法说明】(1) 有些后接双宾语的动词(如buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用for 来引出间接宾语，表示间接宾语为受益者。如： She made her daughter a dress. / She made a dress for her daughter. 她为她女儿做了件连衣裙。 He cooked us some potatoes. / He cooked some potatoes for us. 他为我们煮了些土豆。 注意，类似下面这样的句子必须用for： He bought a new chair for the office. 他为办公室买了张新办公椅。 (2) 注意不要按汉语字面意思，在一些及物动词后误加介词for： 他们决定在电视上为他们的新产品打广告。 误：They decided to advertise for their new product on TV. 正：They decided to advertise their new product on TV. 注：advertise 可用作及物或不及物动词，但含义不同：advertise sth＝为卖出某物而打广告；advertise for sth＝为寻找某物而打广告。如：advertise for a job=登广告求职。由于受汉语“为”的影响，而此处误加了介词for。类似地，汉语中的“为人民服务”，说成英语是serve the people，而不是serve for the people，“为某人的死报仇”，说成英语是avenge sb’s death，而不是avenge for sb’s death，等等。用法3：(表用途)用于，用来。如： Knives are used for cutting things. 小刀是用来切东西的。 This knife is for cutting bread. 这把小刀是用于切面包的。 It’s a machine for slicing bread. 这是切面包的机器。 The doctor gave her some medicine for her cold. 医生给了她一些感冒药。 用法4：为得到，为拿到，为取得。如： He went home for his book. 他回家拿书。 He went to his friend for advice. 他去向朋友请教。 She often asked her parents for money. 她经常向父母要钱。

XX年日语敬语用法总结

XX年日语敬语用法总结 尊敬语(そんけいご)，抬高对方的地位,对其使用尊敬的语言,不但对表示尊敬的人,包括与这个人有关的动作，状态，所有物品等全都使用尊敬的语言表现。本文为大家准备日语敬语的6个用法归类总结，你都会了吗?快来学习吧! ①お+动词连用形+になる 先生はもうお帰りになりましたか。 ②お/ご+动词词干+です 先生はもうお帰りですか。 ③お/ご+动词连用形+くださる 山田先生が文法をお教えくださいます。 ④お/ご～なさる そんなにご心配なさらないでください。 早くお電話なさったほうがいいと思います。 动词的未然形+れる/られる(敬语助动词) 例： 先生の考えられたとおりです。 先生、もう帰られますか。 课长も行かれるそうです。 いつお国へ帰られますか。 ア お+五段动词或一段动词连用形+になる

如：「先生はもうお帰りになりますか。」“老师您要回去了吗?” 「先生は何时ごろ御出勤になりますか。」“老师您几点上班?” 这里要注意： a，当动词的连用形只有一个字母(兼用一段动词)时，不用这个句形。 b，动词是敬语动词时，不用这个句型。 c，外来语构成的动词，不用这个句型。 イ ご(御)+さ变动词词干+です 如：「先生はもうお帰りですか。」“老师您要回去了吗?” 「先生は何时ごろ御出勤ですか。」“老师您几点上班?” 这里注意： a，这个句形没有时态变化，时态用相关的副词表示。 如：(将来时)「先生は明日お帰りですか。」“老师明天回去吗?”(现在时)「先生は今お帰りですか。」“老师现在回去吗?”(过去时)「先生はもうお帰りですか。」“老师已经回去了吗?” b，存じる是知る的自谦语，但是可用这个句形，表示尊敬。 如：「先生ご存じですか。」“老师，您知道吗?” ウ お+五段动词或一段动词连用形+くださる

中考英语现在进行时知识点总结

中考英语现在进行时知识点总结 一、初中英语现在进行时 1．—Did you hear someone knocking at the door just now, Tom? —No, I _______ TV with my friend in my bedroom. A. was watching B. watched C. am watching D. watch 【答案】 A 【解析】【分析】句意：——汤姆，你刚才听到有人敲门了吗？——没有，我和我的朋友正在卧室里看电视。A. was watching过去进行时；B. watched一般过去时；C. am watching 现在进行时；D. watch观看，动词原形。根据Did you hear someone knocking at the door just now, Tom?No,可推知刚才有人敲门时我和我的朋友正在卧室里看电视。所以该句强调的是过去某个时间正在进行和发生的动作，确定时态为过去进行时态，其构成为was/were＋现在分词，根据主语是I，故助动词用was，watch的现在分词为watching，故填was watching，故选A。 【点评】考查过去进行时。根据语境和上下文的联系确定句子的时态。 2．The sports meeting in our school now. A. being held B. is having C. is holding D. is being held 【答案】 D 【解析】【分析】句意：在我们学校运动会正在被举行。“be+being +动词的过去分词” 是现在进行时态的被动句的结构。所以选D。 【点评】考查现在进行时的被动语态。 3．A woman with two children ________ along the street at the moment. A. is walking B. are walking C. walk D. walks 【答案】 A 【解析】【分析】句意：一个带着两个孩子的女人此刻正走在大街上。with连接的两个名词作主语是，谓语与with前的名词保持一致。即句子的主语是 a woman，谓语动词用单数，结合at the moment （此刻）可知要用现在进行时，故选A。 【点评】考查主谓一致和现在进行时。 4．Lucy practices singing every evening. Listen, she so loudly. A. is singing B. sings C. sang D. singing 【答案】A 【解析】【分析】句意：露西每天练习唱歌。听，她唱得那么大声。根据动词listen，可知这里是此时正在进行的动作，用现在进行时：be+doing，结合句意，故答案为A。 【点评】考查现在进行时。掌握进行时的结构和用法。

介词for用法完全归纳

用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for? 你干吗这样做? That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time? 她这次去干什么去了? He was waiting for the bus. 他在等公共汽车。 【用法说明】在通常情况下，英语不用for doing sth 来表示目的。如：他去那儿看他叔叔。 误：He went there for seeing his uncle. 正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。(见下面的有关用法) 用法2：(表利益)为，为了。如： What can I do for you? 你想要我什么? We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me? 请你替我提这个东西好吗? Do more exercise for the good of your health. 为了健康你要多运动。 【用法说明】(1) 有些后接双宾语的动词(如buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用for 来引出间接宾语，表示间接宾语为受益者。如：

最全日语敬语总结,都在这里了~!

礼貌语(丁寧語) 所谓礼貌语是指将语言说得更礼貌、更优美、更有涵养的语言，是敬语当中最简单的一种。 Ⅰ「～です」/「～ます」/「～でございます」 在词尾带有「です」「ます」「でございます」是礼貌语的代表。其中，「です?ます」是礼貌语的基础。 ● 「～です」 上海産業です。/这里是上海产业。 上海の生まれです。/我是上海出生的。 ● 「～ます」 雨が降っています。/在下雨。 ● 「～でございます」(接待客人等场合使用的礼貌说法。) 営業は6時まででございます。/营业时间是到6点。 Ⅱ在前面加「お」或「ご」等接头词(美化语) ● 带「お」的词语 お顔お名前お仕事お食事/お忙しいお電話(する) ● 带「ご」的词语 ご用ご予定ご職業ご理解ご返事/ごゆっくりご案内(する) 注：大多数情况下，片假名前不接「お」或「ご」等接头词。 Ⅲ「お/ご～さま」的句型 先日はご馳走さまでした。/上次承蒙您的款待。 昨日はお世話さまでございました。/昨天承蒙您关照了。 おかげさまで元気です。/托您的福，我很好。 Ⅳ在工作中常用到的正式说法(礼貌语) 一般用语/正式用语 うちの会社/当社、弊社、私ども(本公司) あなたの会社/御社、貴社、そちら様(贵公司) あなた/そちら様 (您) この人/この方、こちらの方(这位) この人たち、先生たち/この方々、先生方 (各位、各位老师) みんな/皆様(诸位) お客さん/(顾客) だれ/どなた、どちら様(哪位) こっち、そっち、あっち/こちら、そちら、あちら(这边、那边、那边) どこ、どっち/どちら(哪边)

どう/(如何) どんな/どのような(什么样的) いくら/いかほど、おいくら (多少钱) 今/ただ今(此时) 今度/この度、この程、今回(此次) さっき/先程(刚才) 後で/後ほど(稍后) これから/今後(今后) 早く/早めに (提前) すぐに/直ちに、早速、早急に(立即、立刻、火速) すぐに交換します。/直ちに交換いたします。(立即更换。) 今日/本日(今天、本日) 明日「あした」、明日「あす」/明日「みょうにち」(明天) 明後日「あさって」/明後日「みょうごにち」 (后天) 次の日/翌日(第二天、次日) 次の次の日/翌々日(第三天) 昨日「きのう」/昨日「さくじつ」(昨天) 一昨日「おととい」/一昨日「いっさくじつ」(前天) この間/先日(前些日子) 今日の夜/今晩、今夜(今晚、今夜) 夕べ/昨晩、昨夜(昨晚、昨夜) 今朝/今朝ほど(今天早晨) 明日の朝/明朝「みょうちょう」(明天早晨) 今年/本年(今年) 去年/昨年(去年) (お客様に)誰ですか。/どちら様でしょうか。(哪一位) 課長、社長が呼んでますよ。/課長、社長がお呼びです。(课长，社长在喊您。) 席にいません(社内)。/席を外しております。 (离开座位了。) 会社にいません(社外)。/出かけております、外出しております、外出中でございます。(外出了。) いい/よろしい、結構(很好、可以) もう一度/改めて(重新) すごく、とても/たいへん、非常に(相当、非常) 本当に/誠に(实在、真的) ちょっと、少し/少々(稍微) 少し待ってください。/少々お待ちください。(请稍候。) はい、わかりました。/(好，我知道了。) その件はわかりません。/その件はわかりかねます。(我不清楚那件事。) それはできません。/それはいたしかねます。(那个很难做。) そうします。/そのようにいたします。(照那样办。) はい、そうです。/はい、さようでございます。(对，就是那样。) これでいいですか。/これでよろしいでしょうか、これでよろしゅうございますか。(这样可以吗？) (商品が)ありません。/切らしております。(脱销了。)

现在进行时用法

个性化教学辅导教案 姓名周咏杰年级七性别男总课时第6 次课 教学目标1·现在进行时的用法 2·现在进行时还可以表示将来时 难点重点教学重点：掌握现在进行时的基本用法 教学难点：将现在进行时的用法用于实际解题、和写句子当中 课堂教学过程课前 检查作业完成情况：优□良□中□差□建议 过 程 一·知识呈现 现在进行时用法 1、现在（说话的瞬间）正在进行或发生的动作，强调“此时此刻”。一般由look, listen, now, at this moment等时间状语做标志（也就是告诉你该句子要用进行时态）。 E.g. Look，He is reading.看！他在阅读 They are talking now.他们现在在谈话 2、当前一段时间内一直在进行的动作。 E.g. They are working these days. 这些天，他们一直在工作 3·现在进行时与always, often,等连用表示赞扬、厌烦等语气。如： Eg，My father is always losing his car keys. 我爸老丢车钥匙。(不满) 难点⊙4、某些动词的现在进行时，表预定的计划或即将发生的动作（常与一个表示将来的时间状语连用）。 E.g I am coming tomorrow.明天我要来、我将会来。 二·小试牛刀翻译下列句子 She is opening the window now. Who is cleaning the window? She is not closing the door now. I am doing your homework. They are singing under the tree now. They’re having a meeting. I’m studying at an evening school. ‘ They’re having a party next week

for的用法完全归纳

for的用法完全归纳 用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for? 你干吗这样做？ That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time? 她这次去干什么去了？ He was waiting for the bus. 他在等公共汽车。 在通常情况下，英语不用for doing sth 来表示目的。如：他去那儿看他叔叔。 误：He went there for seeing his uncle.正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。 用法2：(表利益)为，为了。如： What can I do for you? 你想要我什么？ We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me? 请你替我提这个东西好吗？ Do more exercise for the good of your health. 为了健康你要多运动。 (1)有些后接双宾语的动词(如buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通 常用for 来引出间接宾语，表示间接宾语为受益者。如： She made her daughter a dress. / She made a dress for her daughter. 她为她女儿做了件连衣裙。 He cooked us some potatoes. / He cooked some potatoes for us. 他为我们煮了些土豆。 注意，类似下面这样的句子必须用for： He bought a new chair for the office. 他为办公室买了张新办公椅。 (2) 注意不要按汉语字面意思，在一些及物动词后误加介词for： 他们决定在电视上为他们的新产品打广告。 误：They decided to advertise for their new product on TV. 正：They decided to advertise their new product on TV. 注：advertise 可用作及物或不及物动词，但含义不同：advertise sth＝为卖出某物而打广告；advertise for sth＝为寻找某物而打广告。如：advertise for a job=登广告求职。由于受汉语“为”的影响，而此处误加了介词for。类似地，汉语中的“为人民服务”，说成英语是serve the people，而不是serve for the people，“为某人的死报仇”，说成英语是avenge sb’s death，而不是avenge for sb’s death，等等。 用法3：(表用途)用于，用来。如： Knives are used for cutting things. 小刀是用来切东西的。 This knife is for cutting bread. 这把小刀是用于切面包的。 It’s a machine for slicing bread. 这是切面包的机器。 The doctor gave her some medicine for her cold. 医生给了她一些感冒药。 用法4：为得到，为拿到，为取得。如： He went home for his book. 他回家拿书。 He went to his friend for advice. 他去向朋友请教。 She often asked her parents for money. 她经常向父母要钱。 We all hope for success. 我们都盼望成功。 Are you coming in for some tea? 你要不要进来喝点茶？ 用法5：给(某人)，供(某人)用。如： That’s for you. 这是给你的。 Here is a letter for you. 这是你的信。 Have you room for me there? 你那边能给我腾出点地方吗？ 用法6：(表原因、理由)因为，由于。如：

何时用敬语 办公室谈吐礼仪

何时用敬语办公室谈吐礼仪 语言是双方信息沟通的桥梁，是双方思想感情交流的渠道。语言在人际交往中占领着最基本、最重要的位置。语言作为一种表达方式，能随着时刻、场合、对象的别同，而表达出各种各样的信息和丰富多彩的思想感情。语言表达出来。说话礼貌的关键在于尊重对方和自我谦让。要做到礼貌说话必须做到以下几点： 一、使用敬语、谦语、雅语 （一）敬语 敬语，亦称“敬辞”，它与“谦语”相对，是表示恭敬礼貌的词语。除了礼貌上的必须之外，能多使用敬语，还可体现一具人的文化修养。 １、敬语的运用场合 第一，比较正规的社交场合。 第二，与师长或身份、地位较高的人的交谈。 第三，与人初次打交道或会见别太熟悉的人。 第四，会议、谈判等公务场合等。 ２、常用敬语 我们日常使用的“请”字，第二人称中的“您”字，代词“阁下”、“尊夫人”、“贵方”等，另外还有一些常用的词语用法，如初次见面称“久仰”，很久别见称“久违”，请人批判称“请教”，请人原谅称“包涵”，烦恼别人称“打搅”，托人办事称“拜托”，赞人见解称“高见”等等。（二）谦语 谦语亦称“谦辞”，它是与“敬语”相对，是向人表示谦恭和自谦的一种词语。谦语最常用的用法是在别人面前谦称自己和自己的亲属。例如，称自己为“愚”、“家严、家慈、家兄、家嫂”等。自谦和敬人，是一具别可分割的统一体。虽然日常日子中谦语使用别多，但其精神无处别在。只要你在日常用语中表现出你的谦虚和恳切，人们自然会尊重你。 （三）雅语 雅语是指一些比较文雅的词语。雅语常常在一些正规的场合以及一些有长辈和女性在场的事情下，被用来替代那些比较随便，甚至粗俗的话语。多使用雅语，能体现出一具人的文化素质以及尊重他人的个人素养。 在待人接物中，要是你正在款待客人，在端茶时，你应该说：“请用茶”。假如还用点心款待，能够用“请用一些茶点。”如果你先于别人结束用餐，你应该向其他人打招呼说：“请大伙儿慢用。”雅语的使用别是机械的、固定的。只要你的言谈举止彬彬有礼，人们就会对你的个人修养留下较深的印象。只要大伙儿注意使用雅语，必定会对形成文明、高尚的社会风气大有益处，并对我国整体民族素养的提高有所帮助。 二、日常场合应对 （一）与人保持适当距离 说话通常是为了与别人沟通思想，要达到这一目的，首先固然必须注意说话的内容，其次也必须注意说话时声音的轻重，使对话者可以听知道。如此在说话时必须注意保持与对话者的距离。说话时与人保持适当距离也并非彻底出于思考对方能否听清自己的说话，另外还存在一具怎么样才更合乎礼貌的咨询题。从礼仪上说，说话时与对方离得过远，会使对话者误认为你别愿向他表示友好和亲近，这显然是失礼的。但是假如在较近的距离和人交谈，稍有

现在进行时用法归纳

现在进行时用法归纳 基本用法： 1. 表示说话时正在进行的动作，强调“此时此刻”，常和now, look, listen连用。 Look! A train is coming. 看，火车来了。 Listen! He is playing the piano. 听，他在弹琴。 2. 表示现阶段正在进行的事情，不一定说话时正在进行。常和at present ,this week ,these days…等时间状语连用。 What lesson are you studying this week? 你们本周学哪一课了？（说话时并不在学） 3. 现在进行时有时可用来表示一个最近按计划或安排要进行的动作，即用现在进行时代替一般将来时， 动词一般多为表示位置移动的动词。如：go, come, leave等。 Where are you going? 你去哪？ I am coming. 我来了。 Are you going to Tianjin tomorrow? 你明天去天津吗? How many of you are coming to the party next week? 你们有多少人下周要来参加晚会？ 4. wear用现在进行时表示一种状态。如： He is wearing a blue coat. 他穿着一件蓝外套。 5. 有些动词意思只是表示一种状态，不能用于现在进行时。如：have(有)，like等。 Now each of us has a dictionary. 现在我们每一个人都有一本词典。 6. 现在进行时与always, often, forever等连用表示赞扬、厌烦等语气。该知识点仅作了解之用， 不作为中考考查内容。如： You’re always interrupting me! 你老打断我的话!(抱怨) My father is always losing his car keys. 我爸老丢车钥匙。(不满) She’s always helping people. 她老是帮助别人。(赞扬)

介词for 的常见用法归纳

介词for 的常见用法归纳 贵州省黔东南州黎平县黎平一中英语组廖钟雁介词for 用法灵活并且搭配能力很强，是一个使用频率非常高的词，也是 高考必考的重要词汇，现将其常见用法归纳如下，供参考。 1.表时间、距离或数量等。 ①意为“在特定时间，定于，安排在约定时间”。如： The meeting is arranged for 9 o’clock. 会议安排在九点进行。 ②意为“持续达”，常于last、stay 、wait等持续性动词连用，表动作持续的时间，有时可以省略。如： He stayed for a long time. 他逗留了很久。 The meeting lasted （for）three hours. 会议持续了三小时。 ③意为“（距离或数量）计、达”。例如： He walked for two miles. 他走了两英里。 The shop sent me a bill for $100.商店给我送来了100美元的账单。 2. 表方向。意为“向、朝、开往、前往”。常与head、leave 、set off、start 等动词连用。如： Tomorrow Tom will leave for Beijing. 明天汤姆要去北京。 He put on his coat and headed for the door他穿上大衣向门口走去。 介词to也可表示方向，但往往与come、drive 、fly、get、go、lead、march、move、return、ride、travel、walk等动词连用。 3.表示理由或原因,意为“因为、由于”。常与thank、famous、reason 、sake 等词连用。如: Thank you for helping me with my English. 谢谢你帮我学习英语。 For several reasons, I’d rather not meet him. 由于种种原因，我宁可不见他。 The West Lake is famous for its beautiful scenery.西湖因美景而闻名。 4.表示目的,意为“为了、取、买”等。如: Let’s go for a walk. 我们出去散步吧。 I came here for my schoolbag.我来这儿取书包。 He plays the piano for pleasure. 他弹钢琴是为了消遣。 There is no need for anyone to know. 没必要让任何人知道。 5.表示动作的对象或接受者,意为“给、为、对于”。如: Let me pick it up for you. 让我为你捡起来。 Watching TV too much is bad for your health. 看电视太多有害于你的健康。 Here is a letter for you. 这儿有你的一封信。

for循环的使用和用法

简单的来说，++i 和i++,在单独使用时，就是i=i+1。 而a = ++i，相当于i=i+1; a = i; 而a = i++，相当于 a = i; i=i+1; 如果实在搞不明白++ --怎么回事，那也不是什么天塌下来的事。 因为a=++i完全可以写成i++; a=i。 a=i++完全可以写成a=i; i++。 而且，这也是一种好的程序风格：++ -- 语句如非特殊需要，请单独一行使用。假设i=1 如果执行a=i++ 完之后, a=1, i=2 如果执行a=++i 结果是, a=2, i=2 要分清楚++i,和i++的区别. i++是先执行当前命令,再执行递增. ++i是先递增,再执行命令 缺点： 对于数组，不能方便的访问下标值； 对于集合，与使用Interator相比，不能方便的删除集合中的内容（在内部也是调用Interator）. 除了简单遍历并读取其中的内容外，不建议使用增强的for循环。 一、遍历数组 语法为: for (Type value : array) { expression value; } //以前我们这样写： void someFunction () {

int[] array = {1,2,5,8,9}; int total = 0; for (int i = 0; i < array.length; i++) { total += array[i]; } System.out.println(total); } //现在我们只需这样写（和以上写法是等价的）： void someFunction () { int[] array = {1,2,5,8,9}; int total = 0; for (int n : array) { total += n; } System.out.println(total); } 这种写法的缺点： 显而易见，for/in(for each)循环自动控制一次遍历数组中的每一个元素，然后将它赋值给一个临时变量（如上述代码中的int n），然后在循环体中可直接对此临时变量进行操作。这种循环的缺点是： 1. 只能顺次遍历所有元素，无法实现较为复杂的循环，如在某些条件下需要后退到之前遍历过的某个元素；

英语语法现在进行时归纳总结

英语语法现在进行时归纳总结 一、单项选择现在进行时 1．-- I am afraid I can’t help you with your project. I ________ a model these days. -- It doesn’t matter. I will finish it by myself. A．make B．will be making C．am making D．have made 【答案】C 【解析】 试题分析：考查动词时态。句意：我恐怕不能帮你完成项目了，这几天我要做一个模型。没关系，我会自己完成。表示这几天一直要做的事情，用一般现在时表示将来，故选C 项。 考点：考查动词时态 2．—I some courses at university，so I can’t work full time at the moment． A．take B．am taking C．took D．have taken 【答案】B 【解析】 试题分析：考查动词的时态。句意：因为我正在上学，所以不能在这时候做全职的工作。根据下方提到so I can’t work full time at th e moment 可知我正在上学，故选B 项。 考点 : 考查动词的时态 3．The water supply has been cut off temporarily because the workers the main pipe．A．repair B．repaired C．have repaired D．are repairing 【答案】D 【解析】 试题分析：考查动词的时态。句意：因为工人正在修理主管道，所以水供应暂时被切断。根据语境表示，修理管道这件事正在进行，所以选D项。 考点 : 考查动词的时态 4．– Do you think we should accept that offer? -- Yes, we should, for we ___such bad luck up till now, and time __ out. A．have had; is running B．had; is running C．have; has been run D．have had; has been run 【答案】A 【解析】 【详解】 考查动词的时态。 句意：---你认为我们应该接受那个建议吗？ ---是的，我们应该，因为到目前为止我们已经运气很糟糕，并且时间也正在被耗尽。

小学英语现在进行时详解及试题

小学英语现在进行时详解及试题 一、构成：由be(am/is/are)+动词-ing形式构成。标志性词语： 1.现在进行时通常用“now”.如I am doing my homework now. 2.现在进行时通常用“look”. 如Look! My mother is running. 3.现在进行时通常用“listen”如Listen! They are reading. 4.现在进行时通常用“at the (this) moment” 如At the (this) moment，he is only weeping. 二、动词现在分词的构成规则 1 一般情况下直接加ing think---thinking sleep---sleeping study---studying 2 以不发音的字母e结尾的单词，去掉字母e，再加ing come---coming make---making have---having 3以重读闭音节（重读闭音节即两个辅音中间夹一个元音并且重读的音节）结尾，呈现“辅，元，辅”结构的动词，双写末尾的辅音字母，再加ing stop---stopping sit---sitting run---running 这类词还有：bigin，cut，get，hit，run，set，sit，stop，swim等。 4以ie结尾的动词，把ie改为y ，再加ing die---dying lie---lying 三、现在进行时的用法 （1）用来表示说话时正在进行或者发生的动作， 例如：Mother is cooking in the kitchen.妈妈在厨房里煮饭。 （2）用来表示现阶段正在进行的动作（但说话时不一定在进行）， 例如：Is she writing a novel? 她正在写一本小说吗？ （3）用来表示即将发生的动作，一般是指按计划或者安排好要发生的动作。适用于这种情况的动词主要有：go，come，leave，start，arrive等。例如: I’m going home in half an hour.我一个半小时内要回家。

for的用法完全归纳

f o r的用法完全归纳 TTA standardization office【TTA 5AB- TTAK 08- TTA 2C】

f o r的用法完全归纳用法1：(表目的)为了。如： They went out for a walk. 他们出去散步了。 What did you do that for 你干吗这样做 That’s what we’re here for. 这正是我们来的目的。 What’s she gone for this time 她这次去干什么去了 He was waiting for the bus. 他在等公共汽车。 在通常情况下，英语不用 for doing sth 来表示目的。如：他去那儿看他叔叔。 误：He went there for seeing his uncle.正：He went there to see his uncle. 但是，若一个动名词已名词化，则可与 for 连用表目的。如： He went there for swimming. 他去那儿游泳。(swimming 已名词化) 注意：若不是表目的，而是表原因、用途等，则其后可接动名词。 用法2：(表利益)为，为了。如： What can I do for you 你想要我什么 We study hard for our motherland. 我们为祖国努力学习。 Would you please carry this for me 请你替我提这个东西好吗 Do more exercise for the good of your health. 为了健康你要多运动。 (1)有些后接双宾语的动词(如 buy, choose, cook, fetch, find, get, order, prepare, sing, spare 等)，当双宾语易位时，通常用 for 来引出间接宾语，表示间接宾语为受益者。如：

敬语

得体地使用敬语始终是学习日语中的一大难点。这里主要要解决习惯问题（思维定势问题），记忆一些尊敬语的定式对正确掌握敬语的用法很重要。本期简要归纳这部分内容，后面附练习题供大家巩固知识。 一、尊敬语--- 抬高对方是尊敬语的思维定势。注意：主语是恭维的他人，不能是自己。 1、名词构词法 「お」+和語：名前--->お名前；知らせ--->お知らせ；心配り--->お心配り。 「ご」+漢語：氏名--->ご氏名；通知--->ご通知；心配--->ご心配。 汉字词中例外用「お」构词的：お写真、お道具、お辞儀、お題、お熱、お帽子。 2、助动词短语构词法 お（ご）～になる：帰る--->お帰りになる；読む--->お読みになる；相談--->ご相談になる。 お（ご）～なさる：届ける--->お届けなさる；過ごす--->お過ごしなさる；説明--->ご説明なさる。お（ご）～下さる：書く--->お書きくださる；会う--->お会いくださる；理解--->ご理解くださる。3、一段、五段动词词尾变化表达敬意（れる?られる）----注意：比助词短语形敬意要低 会う--->会われる；書く--->書かれる；過ごす--->過ごされる。 起きる--->起きられる；述べる--->述べられる；来る--->来られる。 4、添加接头、结尾词 貴：兄--->貴兄；会社--->貴社；ところ--->貴地 さん、様、殿：息子--->息子さん；娘--->お嬢さん（様）、○○会社--->○○会社殿。

二、自谦语--- 贬低自己，变相抬高对方是自谦语的思维定势。注意：主语只能是自己而不能安到别人头上去。 1、助动词短语构词法 お（ご）～する：聞く--->お聞きする；案内--->ご案内する；配る--->お配りする。 お（ご）～いたす：見せる--->お見せいたす；誘う--->お誘いいたす；案内--->ご案内いたす。お（ご）～いただく：来る--->お越しいただく；話す--->お話いただく；招待--->ご招待いただく。～ていただく：会う--->会っていただく；話す--->話していただく；歓迎--->歓迎していただく。 お（ご）～申し上げる：通知--->ご通知申し上げる；願う--->お願い申し上げる。 お（ご）～願う：送る--->ご送付願う；聞く--->お聞き願う。 2、人称代词表达谦逊 私、僕、私ども、小生、夫、主人、妻、家内、父、母、おやじ、おふくろ、息子、娘、姉、兄、弟、妹。 3、特殊词汇表达谦逊 粗品、寸志、小著、愚見、私見、拙宅、小社、弊社 三、郑重语--- 虽也表示对对方的敬重，但没有抬高对方或贬低自己的意思在里面。最常用的就是大家都熟悉です?ます体。可能不太熟悉的类型罗列一下。 1、～であります：学生だ--->学生であります；話した--->話したのであります。 2、～おります：家にいる--->家におります；聞いている--->聞いております。 3、～でございます：山田だ--->山田でございます。９月だ--->９月でございます。

高考现在进行时的归纳

高考现在进行时的归纳 一、单项选择现在进行时 1．Kimberly ______ an article, so don’t disturb her. A．would write B．writes C．wrote D．is writing 【答案】D 【解析】 试题解析：本题考查时态，根据句意，选用现在进行时，表示说话时刻正在进行的动作。 A would write 过去将来时，必须和一般过去时结合使用，表示过去的将来； B writes 一般现在时，表示经常、习惯的动作；客观真理；现在的事实或状态；代替一般将来时； C wrote 一般过去时，表示过去的动作，与现在无关。 考点：现在进行时及其被动式 2．Since the band announced the release of their new album, the phone hasn't stopped ringing. Many fans ________ to ask about the exact time. A．were calling B．had called C．are calling D．call 【答案】C 【解析】 C 考察动词时态。句意：自从那支乐队宣布了要发行新的专辑的消息，电话铃声就不停地响。很多粉丝一直都打电话询问具体的发行时间。根据句中的hasn’t stopped ringing可知询问具体的时间内这件事情现阶段正在发生，应该使用现在进行时。故C正确。 3．Hurry up! Mark and Carol ________ us. A．expect B．are expecting C．have expected D．will expect 【答案】B 【解析】 试题分析：考查动词的时态。催促别人快点，因为Mark和Carol正等着呢，适合用现在进行时。 【名师点睛】英语中的时态主要由动词的形式决定，因此在学习英语时态时，要注意分析动词形式及具体语境，想象在那个特定的时间动作所发生的背景，这个动作是经常性动作、一般性动作、进行性动作、完成性动作还是将要发生的动作。由Hurry up！可以判断这个动作正在发生。 4．Hi, Mike. I’ve to borrow your car this afternoon mine _______ in the garage. A．is repairing B．is being repaired C．has repaired D．has been repaired 【答案】B 【解析】