语法基础｜whether, if引导的宾语从句

用whether, if引导，whether, if不能省略，可以互换。从句中用陈述句语序。

例如：

She asked whether you were a dentist．她问你是不是牙科医生。

He was anxious to see if/whether she had relapsed since the previous evening．他急于想去看看，前天晚上以来她的病是否复发了。

Go and see if they are still in the laboratory．你去看看他们是否仍在实验室里。

We doubt if/whether he is telling the true．我们怀疑他是否在讲真话。

Francesca sank but recovered enough to ask the secretary if she had dialed the correct number．弗郎西丝卡的心沉了下来，但还能恢复过来问那女秘书是否她拨的电话号码错了。

I wonder whether the country life will agree with her．我不知道乡村生活是否会适合他。

• 【注1】用whether，正反面的选择较强，可与or或or not连用；用if，则比较强调单方面，或从句是否定式时也用if，不能和or not连用。例如：

He asked me whether he should come（or not）．他问我他是否会来。

I don't know whether I should go away or stay here．我不知道我该走还是留在这里。

He asked me if he could come．他问我他是否能来。

• 【注2】在谓语是doubt的肯定句后接if或whether引导的从句如果是否定句或疑问句，则后接that引导的从句。例如：

We don't doubt that he can do a good job of it．我们并不怀疑他能把这事做得很好。

Does any one doubt that it is so？它原来是这样，有谁怀疑吗？