IV. Answer the following questions:

1. When did man first begin to apply petroleum?

2. How did ancient people use petroleum?

3. What factor has led to the development of modern petroleum industry?

4. How can one define petroleum?

5. Where does petroleum form and accumulate?

6. Does petroleum consist of different hydrocarbons?

7. What impurities does petroleum often contain?

8. What factors does the odour of petroleum depend on?

9. Is the color of oil always dark brown?

10. What determines its colour?

11. Are all sorts of petroleum combustible?

12. Is there a clear explanation for the petroleum formation?

13. Do all scientists admit the organic origin of petroleum?

V. Retell the text using the questions in IV.

VI. Translate the following sentences into Russian, paying attention to the Degrees of Comparison.

1. Only since 19 century A.D. people have begun to use petroleum as one of the most important sources of energy. 2. Very often petroleum engineers drill deeper wells. 3. The deepest wells reach gigantic depths of 10,000 and even more metres. 4. Besides, oil often contains smaller amounts of sulphur, nitrogen and oxygen. 5. The heavier the oil the darker is the colour. 6. Oil is much lighter than water. 7. At present, petroleum is the most important fuel and energy source.

VII. Look at the following words with ending “-s”. Decide whether it is a noun in plural form or a verb in the Present Simple Tense, 3^rd person (text “Petroleum” may be helpful to you).

varies plants animals impurities depends determines

wells accumulates layers conditions forms consists

fluids insulators battles incendiaries centuries depths

purposes properties dwellings diseases ancients contains

VIII. Find one sentence in Present Perfect Tense in the text. Natural gas

1. Translate the following expressions into Russian without a dictionary.

animal and vegetable remains under great pressure several boreholes network of pipelines low boiling point 85 per cent distinct odour

a great amount of heat numerous new sources to obtain new materials over a period of many centuries over long distances inflammable gas CIS = Commonwealth of Independent States

II. Read and translate the text. Natural gas

Natural gas either occurs together with crude oil or forms separate deposits of gas alone. Decomposition of both animal and vegetable remains over a period of many centuries without air is the source of natural gas. A great volume of gas accumulates and penetrates into porous beds of sand, sandstones and limestones. In these beds gas can form natural deposits under great pressure. When a borehole reaches such a deposit the gas rushes up. This gas has to be collected from several boreholes with the help of pipelines over long distances

Natural gas is an inflammable gas and consists of hydrocarbons with a very low boiling point. Methane (CH₄ ) makes up approximately 85 per cent of the typical natural gas. Ethane (C₂H₆) can be present up to 10 % and propane (C₃H₈) up to 3 %. Butane, pentane, hexane, octane and a few other gases may also be present. In contrast to crude petroleum natural gas has no distinct odour.

Little of natural gas we may use chemically, most of it we use as a fuel for the production of both heat and energy. Like all gaseous fuels natural gas has great amount of heat. Natural gas is valuable also as an important chemical raw material for industry, as chemical technologists are able to obtain hydrogen, acetylene, carbon black and various chlorine derivatives.

Natural gas occurs mainly in Russia and some other CIS countries and in the United States where most of the extraction and utilization takes place. Russia has a gigantic network of pipelines.