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We use plastic wrap to protect our foods

We use plastic wrap to protect our foods.We put our garbage in plastic bags or plastic cans.We sit on plastic chairs, play with plastic toys,drink from plastic cups,and wash our hair with shampoo from plastic bottles.Plastic does not grow in nature.It is made by mixing certain things together.We call it a produced or manufactured material.Plastic was first made in the 1860s from plants,such as wood and cotton.That plastic was soft and burned easily.The first modern plastics were made in the 1930s.Most clear plastic starts out as thick, black oil.That plastic coating inside a pan begins as natural gas.Over the years,hundreds of different plastics have been developed.Some are hard and strong. Some are soft and bendable.Some are clear. Some are many-colored.There is a plastic for almost every need.Scientists continue to experiment with plastics.They hope to find even more ways to use them.

Music is the abstract art of arranging vocal or instrumental sounds in a manner that produces a flowing,unified and thoughtful composition that has melody,harmony, rhythm.In contrast to the other arts,music is not a readily tangible form of expression.Music may be called both the most mathematical and the most abstract of the arts.Unlike words, images, or dance, however,musical tones in themselves have no concrete associations,and only gain meaning when they are combined into patterns.Through the centuries various philosophers have attempted to integrate theories on the essence of music with their particular world views.Many non-Western cultures and some Western writers as well have perceived it as an inherently mystical force,able to unlock elemental truths or principles that cannot be translated into written or graphic form.Music is an important part of our lives,and has been an important part of every civilization known to man.

May and June are the months when most American colleges and universities hold their commencements.These ceremonies are a time for family and friends to gather and celebrate a student's completion of an academic degree. Most ceremonies are traditional.The students wear caps and gowns over their clothing.One by one, their names are called.They go to the front, shake hands with school officials and receive a document of some kind.But first they must sit and listen to speeches.Colleges and universities often invite famous guests or former students who have become successful.Schools often want speakers to comment on world events.More recently, the trend has been to find a celebrity or a politician to deliver the http://www.wendangku.net/doc/dadd485633d4b14e852468dc.htmlmon themes of the graduation speech include wishing the graduates well in the "real world",cautioning that the world of academy is a special place where they were taught to think.

The media plays a vital role as a guardian of U.S. democracy.U.S. media have traveled a long road since the first newspaper was published in 1690.Within 50 years, magazines also began appearing in several major American cities.The advent of commercial radio at the beginning of the 20th century ended print's monopoly of the media in America,giving nationwide and, later,global audiences unprecedented access to live audio programs.Television, an even more powerful medium,entered the scene shortly after World War II.Defying predictions of their decline,the other media have diversified to confront television's dominant appeal.Satellite technology has allowed U.S. TV networks,especially cable networks,to reach overseas audiences anywhere on the globe.Interactive media, fueled by the advance of digital technology and the growing convergence of the computer,telephone and cable television,represent the principal trend of the end of the 20thand the beginning of the 21st centuries.