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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. Russia has a gigantic network of pipelines.
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 (C2 H6 ) can be present up to 10 % and propane ( C3 H8 ) 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 gives a 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. Before the war we utilized gas only at Baku and in the Carpathian Mountains. Since then they have discovered numerous new sources, for example , in the Ukhta (Russia) and Emba regions (Kazakhstan), near Saratov, Fergana (Uzbekistan), Samara, Volgograd and Grozny. In Europe they found rich deposits in Rumania and Italy, smaller ones in Austria and France. Germany also has several small but intensively worked fields.
1. Maria got some bad news last week. She has been sad since she got the bad news.
2. I started school when I was five years old. I have been at school since I was five years old.
3. I have changed my job three times this year.
4. I changed my job three times last year.
5. The weather was hot and dry for many weeks. But two days ago it rained.
6. Tom broke his leg five days ago. He’s in hospital. He has been in hospital since he broke his leg.
7. Are you going to finish your work before you go to bed? — I have already finished it . I finised my work two hours ago.
On the one hand a 50 year period for the country is not very long but on the other hand great changes have been rapidly taking place in this country since the 70s. What are these changes? First of all I'd like to mention the development of new technologies in modern society, for example wireless connection, appearance of the mobile phones. For people from that time it was fantastic but for all of us its quite an ordinary thing today. Then we can't stand mentioning the Internet that is a necessary thing almost everywhere nowadays and it's difficult to imagine how people lived, worked and studied without computers at that time.To my mind the life in this country now became more complicated than it was 50 years ago, but more challenging and interesting.