单项选择题

We can conclude that ______.

A．civilization may be doomed if pollution is not controlled
B．pollution is more serious in Europe than it is in America
C．most people do not know that pollution is a serious problem
D．black snow is not so serious compared with white snow

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热门试题

单项选择题

Air pollution causes airplane accidents because ______.

A．pilots become ill
B．visibility is reduced
C．engines fail.
D．the air is too hot

单项选择题

In author’s opinion, ______.

A．without computers, there would be no modern science
B．computers are more intelligent than human beings
C．computers will replace everything in the future
D．computers never make mistakes