?

1. C。

【解析】：參閱第一段第二句。It is a problem to nearly everyone at some time 。

2．B。

【解析】：房間暗有助睡眠，這是常識(shí)。參閱第二段中間。If it is not dark enough, or too noisy, this may cause difficulty in sleeping。

3．D。

【解析】：參閱第四段最后一句。Above all, he should try not to worry about sleeplessness when someone is tied enough he nearly always falls asleep。

4．D。

【解析】：同上一題。