A.therefore
B.but
C.moreover
D.besides

A.behave
B.allow C. remind D. enter
C.
D.

A.determine
B.pollution C. essential D. charity
C.
D.

A.accurately and objectively
B.harder and harder
C.on social and political purposes
D.with other social scientists

A.To conduct a survey of the biologist's role in society.
B.To emphasize the biologist's role in solving the world's problems.
C.To urge biologists to solve the problem of surplus human population.
D.To advise biologists to carry out extensive research into genetic engineering.

A.is the most desirable for life
B.may do us more harm than good
C.will change all human traits
D.is no longer desirable

A.genetic engineering misuse
B.social and economic deficiencies
C.environmental pollution D. manipulation of genes
D.

A.the development of new ideas
B.his basic research
C.his manipulation of genes D. the consequences of his discoveries
D.

A.serious environmental pollution
B.activities of an overpopulated society's industry
C.activities of surplus human population
D.the waste products dumped into our environment

A.The workers at the factory shouldn’t wear protective clothing.
B.The workers at the factory must wear protective clothing.
C.The workers at the factory needn’t wear protective clothing.
D.The workers at the factory may wear protective clothing.