单项选择题

It is believed that ______.

A．overpopulation causes the problems in cities
B．two-thirds of the world' s population are living in cities today
C．it isn' t difficult to solve the problems faced by cities today
D．with fewer people, we would be free from any problems

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热门试题

单项选择题

The species of black spiders discovered on Mount Everest is ______.

A．the smallest species of spiders
B．the highest altitude dweller among creatures of that size or larger
C．the only creature that lives at that altitude
D．capable of surviving in any environment

单项选择题

Small animals are said to live faster than big ones because they ______.

A．have more skin for every ounce of body weight
B．replace lost heat faster
C．bum fuel faster
D．maintain a higher body temperature