Big cities suffer from smog from large factories. Cars with their engines have become the main source of pollution in industrial countries. The forests Africa, South America and Asia are cut down for the needs of industries in Europe and the USA. As a result some species of animals, birds, fish and plants have disappeared and keep disappearing. Rivers and lakes dry up. One of the most known examples is the Aral Sea, which has become much smaller due to men’s activity.
The pollution of the air and of the world’s oceans and the thinning of the ozone layer nowadays are the main problems arising from man’s careless attitude to ecology.
In Russia and the former Soviet republics there are some areas where the environment is in a poor state. The Aral Sea, Lake Baikal, the Kuzbass, Semipalatinsk and Chernobyl are such problematic regions.
For decades nuclear weapons were tested near Semipalatinsk, and the ground is contaminated with radiation there.
More than 20 years ago a pulp-and-paper factory was built on the shore of Lake Baikal. As a result of the pollution, more than 50 % of the world’s purest water has been ruined. The whole ecological system of the lake has change greatly.
2It is washed by the Atlantic Ocean in the east and by the Pacific Ocean in the west.
3It stretches from Canada in the north to Mexico in the south.
4In size the USA is the fourth after Russia, Canada and China.
5It has many islands in the Pacific Ocean and Puerto Rico and the Virgin Islands in the Atlantic.
6This great country has a lot of mountains, rivers and lakes.
7The main mountains are the Appalachian mountains and the Cordilleras.
8The longest rivers are the Mississippi and the Missouri.
9The norh-eastern part of the USA is the region of the five Great Lakes(Lake Superior,Huron,Michigan,Erie, and Ontario).
10The climate in the southern part is subtropical while the northern part has a very cold weather in winter.