2015-04-01
1080
Plastics
Plastics are substances, natural and artificial, which can be moulded into any desired shape by the application of heat and pressure. Expert for cellulosic, made from chemically modified cotton, wood and other materials, plastics are produced by synthesis from such natural resources as water, air, coal, salt and natural gas.
There are two reasons why man tries to make these materials instead of the ones provided by nature. One reason is his desire either to decrease cost or to compensate for the shortage of the natural product, or both. The second reason is the wish to produce materials with combinations of desirable properties not found in things provided by nature.
There are organic and inorganic synthetics. The difference between organic and inorganic compounds is simply that the former contain carbon, white and the latter do not. One of the most important inorganic synthetic is glass. Because many resource materials are available and many different combinations are possible, the plastics family is very large and is constantly growing larger. Because of their toughness, lightness, chemical resistance and other useful properties as well as the ease of manufacture, plastics products are being used in large quantities in construction, electric and electronic equipment, transportation, agriculture, etc. Synthetic plastics often take the place of metals in machine building and in many respects their properties are higher than that of metals. Russian scientists discovered that some polymers possess really remarkable properties which in some respects are similar to those of iron, although in in a much weaker form. For example, plastics long considered as excellent electrical insulators, can be made to conduct the electricity even as well as some metals. Semiconduction was observed in more than 200 types of plastics, or polymers.
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The extensive use of synthetic materials, however, does not mean the natural materials should lose their importance. On the contrary, when combined with synthetic materials they may become even more valuable. However, scientists say that the most typical materials of the future will be various synthetics. These materials, developed by chemists in the past few decades, will occupy a very important place in industry, construction and the home. They really have a bright future.
Вариант № 4
1. Вставьте один из модальных глаголов по смыслу и переведите предложения:
1. Don’t go to the wood alone: you … lose your way.
2. I have very little time: I … go.
3. Do you … my help?
4. You … wear a raincoat, it will be a rain today.
5. … you speak English?
2. Дайте правильный перевод следующих предложений, обращая внимание на инфинитив:
1. Sorry to have placed you in this disagreeable situation.
2. Clyde was awfully glad to have renewed his acquaintance with Sondra.
3. Sorry not to have noticed you.
4. The children were delighted to have been brought to the circus.
5. To get this book you must go to the library.
3. Раскройте скобки, употребляя глагол в Passive или Active:
1. Many houses (to burn) during the Great Fire of London.
2. The porter (to bring) your luggage to your room.
3. From the station they (to take) straight to the hotel.
4. New film (to bring) yesterday.
5. I (to ask) to open my mouth by doctor.
4. Переведите предложения, обращая внимание на причастие:
1. When speaking English pay attention to the order of the words.
2. The speaking doll interested the child very much.
3. The word spoken in time may have very important result.
4. When sending a telegram she forgot to write her name.
5. The word said by student wasn’t correct.
