2017-10-25
1186
1. Iron is the commonest of all metallic elements (symbol Fe), used in various forms. Practically all of the iron is extracted from its chemical compounds in the blast furnace. A certain amount of harmful impurities is always present in iron ore. Ferrous metals are used in industry in two general forms: cast iron and steel.
Steel is iron containing to 1.7 per cent carbon content. Pure iron is not used in industry because it is too soft.
Cast iron is a hard, brittle, non-malleable iron-carbon alloy containing 2.0 to 4.5 % carbon, 0.5 to 3% silicon and lesser amounts of sulphur, manganese and phosphorus.
2. The chemical process for extracting a metal from its ore is called smelting. Iron ore is heated with limestone and coke, which is mostly made up of carbon. Coke and limestone remove the unwanted parts of the iron ore to leave almost pure iron, which still contains some carbon. Steel is made by removing more carbon and adding other metals.
3. Gold is much softer than copper, so it is easier to hammer into shape. It is not very strong. A gold knife might look very fine but would not have been much use for skinning a bear, so from early times gold became the metal for ornaments. Copper is much harder; it would have been much more difficult for early man to shape; but the finished article was more durable.
4. These metal-workers were masters of the ancient craft of gold-beating, a process by which gold is beaten between skins until it is reduced to a very thin sheet. The Egyptians could produce sheets only one five-thousandth of an inch thick, and used them for gilding wooden statues and for other decorative purposes.
5. In addition the rapid developments in the use of iron and steel during the Industrial Age brought with them greatly increased demand for other metals, particularly copper, tin and lead. Moreover, the demand was not only for greater tonnages but also for a far greater variety of metals. Many of these metals were one hundred years ago little known names in the periodic table, but have now come into prominence and have become marketable commodities.
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Вариант 7
1. Поставьте предложения в страдательный залог (Образец: Mother waters the flowers in the evening. — The flowers are watered in the evening (by mother). Переведите исходное предложение и предложение в страдательном залоге.
1. The North Sea and the English Channel separate Great Britain from the European continent. 2. The designer has been erecting this museum of history for 5 years. 3. They equipped the rocket with six engines having a total capacity of 20 million h.p. 4. Students will translate a very difficult text at the next lesson. 5. Before holidays Muscovites decorate the streets of the city with flags, flowers and decorations.
2. Раскройте скобки, употребляя глаголы в Active или Passive Voice. Переведите предложения.
1. These data (are often referred to/refer to). 2. This phenomenon (will be spoken about/will speak). 3. This method (was used/ used) often because it saved time.. 4. The students (will show/will be shown) well-equipped lecture halls to their foreign students. 5. Workers (are building/are being built) a new office of a well-known company at present.
3. Раскройте скобки, употребляя глаголы в Passive Voice. Переведите предложения.
1. She (to listen) to by everybody yesterday. 2. Papers after the conferences (to publish) often. 3. The results of his ten-year work (to refer to) by many scientists by last month. 4. His scientific work in the field of chemistry (to take notice of) next lecture. 5. His writings (to know) all over the world very often.
