We are all destroying the earth. The seas and the rivers are too dirty to swim in. There’s so much smoke in the air that it’s unhealthy to live in many of the world’s cities. In one well-known city, for example, poisonous gases from cars pollute the air so much that traffic policemen have to wear oxygen masks. We have cut down so many trees that there are now vast areas of waste land around the world. Farmers in parts of Africa cann’t grow enough food to eat. In certain countries in Asia there’s too little rice. Moreover, we don’t take enough care of the countryside. Wild animals are quickly disappearing. For instance, tigers’re rare in India now as lots of them have been killed. Therefore, we must act now before it’s too late to do anything about it. Join us now. Save the earth. 40. Why can’t we swim in the seas and the rivers? A. because they are too dirty. B. because they are too healthy. C. because they are too harmful. D. because there is too much smoke. 41. How is the air in many of the world’s cities? A. It is very pure B. There is so much smoke in it. C. It is healthy for people to breathe. D. All of them are incorrect. 42. What kinds of animals are rare in India now? A. lions B. tigers C. elephants D. bears 43. The result of cutting down trees in Asia and Africa is________ A. farmers in parts of Africa cannot grow enough food to eat. B. there is too little rice in Asia. C. wild animals are not disappearing. D. A and B are correct.