1. Air pollution is a major cause of diseases or even lung cancer.

A.reason B. right C. action D. damage

2. It is found that endangered species are often concentrated in areas that are poor and densely populted, such as much of Asia and Africa.

A.disappeared B. threatened C. increased D. reduced

3 What would happen to man's health if the water rsources were polluted?

A.refined B. contaminated C. destroyed D. poisoned

4

His policies were beneficial to the economy as a whole.

A.good B. crude C. harmful D. harmless