The history of life on earth has been a history of interaction between alive things and their surroundings. To a large extent, the 1. ______ physical form and the habits of the earth’s vegetation and animal life have been molded by the environment. Considering the whole span of earthly time, the opposite effect, on which life actually 2. ______ modifies its surroundings, has been relative slight. Only in the 3. ______ present century have one species—man acquired significant power 4. ______ to alter the nature of his world. During the past quarter century this power has not only become increasingly great but it has changed in character. The most alarming of all man’s assaults upon the environment is the pollution of air, earth, rivers, and sea with danger and even lethal 5. ______ materials. This pollution is for the most part recoverable. In this 6. ______ now universal pollution of the environment, chemicals are the sinister partners of radiation in changing the very nature of the world and the very nature of its life. Chemicals sprayed on croplands (农田) or forests or gardens lie long in soil, enter into 7. ______ living organisms, passing from one to other in a chain of poisoning 8. ______ and death. Or they pass mysteriously by underground streams until they emerge and combine into new forms that kill vegetation, sicken cattle, and work unknown harm on those that drink from 9. ______ once pure wells. "Man can hardly even recognize the devils of his own creation," as a scientist has said. It took hundreds of millions of years to product the life that 10. ______ now inhabits the earth. Given time—time not in years but in millennia—life adjusts, and a balance has been reached. But in the modem world there is no time.