Variant 1 You could have come first and won the race if you … faster

28. The author states that ...

A) hydroelectric plants put dirty water back into the environment

B) thermal pollution occurs when the temperature of a river or lake is raised

C) aquatic life is merely disturbed by thermal pollution

D) thermal pollution is more dangerous than pollution from rubbish or chemicals

29. In the text, what does the author say about rubbish, sewage or chemicals?

A) They have, on occasions, proved to be beneficial to aquatic life.

B) They are all part of the natural environment.

C) They are the main cause of warm water pollution.

D) They can kill aquatic life when they are thrown into the water.