Mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 19 to 24.

We are slowly (19)________ the earth. The seas and rivers are too dirty to swim in. There is so much smoke in the air that is unhealthy to live in many of the world’s cities. In one well-known city, for example, (20)________ gases from cars pollute the air so much that traffic policemen have to wear oxygen marks.

We have cut (21)________ so many trees that are now vast areas of wasteland all over the world. As a result, farmers in some parts of America can’t grow enough to eat. In certain countries in Asia, there is too little rice. (22)________, we do not take enough care of the countryside. Wild animals are quickly disappearing. For distance, tigers are rare in India now because we have killed too many for them to survive. We must act now before it is too (23)________ to do anything. Join us now. Save the earth. It is (24)________ important to ignore.