We are gradually destroying the Earth. The seas and rivers are too dirty to swim in. There is so much smoke in the air that it is 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 wasteland all over the world. As a result, farmers in parts of Africa cannot grow enough to eat. In certain countries in Asia there is too little rice. Moreover, we do not take enough care of the countryside. Wild animals are quickly disappearing. For instance, tigers are rare in India now because we have killed too many for them to survive. However, it isn't enough simply to talk about the problem. We must act now before it is too late to do anything about it. Join us now. Save the Earth. This is too important to ignore. 1. The seas and rivers nowadays . A. are clean. B. are cleaner than they used to be. C. are dirty enough to swim in. D. are contaminated. 2. According to the passage, smoke . A. is harmful to health. B. is full of the big cities. C. causes a healthy life. D. makes life in big cities busy. 3. In one well-known city, traffic policemen have to wear oxygen masks . A. in order to protect themselves from being injured. B. because there are so many cars on the streets. C. in order not to be recognized. D. because of air pollution. 4. Wild animals are . A. being protected from the natural environment. B. in danger of extinction. C. killed, so they live in the forests. D. so rare that they cannot survive. 5. What's the best title for the passage? A. Conservation B. How to protect the environment C. Save the Earth! D. The Environment