单项选择题

Arctic explorers may catch colds when ______.

A．they are working in the isolated arctic regions
B．they are writing reports in terribly cold weather
C．they. are free from work in the isolated arctic regions
D．they are coming into touch again with the outside world

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热门试题

单项选择题The passage mainly discusses ______.

A．the experiments on the common cold
B．the fallacy about the common cold
C．the reason and the way people catch colds
D．the continued spread of common colds

单项选择题The writer offered ______ examples to support his argument.

A．4
B．5
C．6
D．3