Complete each sentence with one of the words given. Do not use a word more than once.
( balance / fuels / gas / lead / species / chemicals / fumes / greenhouse / pesticide / waste )
1. Factories often dispose of ....................... products in rivers and the sea.
2. The chimpanzee is one of many .................... which will soon be found only in zoos.
3. The earth's atmosphere is growing warmer partly because of the so-called "...................... effect"
4. Many scientists believe that the natural ................... of the world's ecology is threatened.
5. Over-exploitation of fossil ..................... such as coal and oil will lead to an energy crisis.
6. Many people prefer to eat fruit and vegetables which have not been sprayed with .......................
7. Within a few years, .......................... -free petrol will be used throughout Europe.
8. Many household products actually contain ........................... which are harmful to the evironment.
9. In some cities a poisonous smog is created from car exhaust .........................
10. Another cause of global warming is emission of carbon dioxide ...................... from power stations and factories.