Some of the people often ask the same questionthe air has been polluted. A. whether　B. ifC

Some of the people often ask the same question the air has been polluted.
A. whether　
B. if
C. that
D. where

A. whether　B. ifC. that D. where解析：选A。考查同位语从句。句意: 人们经常问同样的问题就是空气是否已经被污染了。根据句意“问题”与“是否”搭配。此处question与the air has been polluted为同位关系, 故用whether引导。【知识拓展】通常用whether不用if的场合①引导主语从句且放在句首时。Whether he will come is still a question. 他是否会来还是个问题。注: 若在句首使用形式主语it, 而将主语从句放在句末, 则有时也可用if来引导。例如: It was not known whether[if]he would come. 不知他是否会来。②引导表语从句时。The question is whether we should go on with the work. 问题是我们是否应该继续进行这项工作。③引导让步状语从句时。Whether he agrees or not, I shall do that. 不管他同意与否, 我都要那样做。④与or连用分别引导两个从句时。例如: I don’t know whether he is wrong or she is wrong. 我不知道是他错了, 还是她错了。⑤用于不定式之前时。例如: I’m not sure whether to stay or leave. 我不知是留还是去。⑥用于介词之后时。It depends on whether the letter arrives in time. 这取决于信是否来得及时。⑦直接与or not连用时。例如: I will write to you whether or not I can come. 我能不能来, 我将写信告诉你。若不是直接与or not用在一起, 则有时也可用if。I don’t know whether[if]he will win or not. 我不知他是否能赢。⑧在某些动词后(如discuss等)通常只用whether。We discussed whether we should hold a meeting. 我们讨论了是否要开一个会。

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