§ 定义 介绍引导从句的词叫引导词像whether `how `what `why ` when这些都是 § 不可省略的连词 1. 介词后的连词 2. 引导主语从句和同位语从句的连词不可省略。 That she was chosen made us very happy. We heard the news that our team had won. 比较：whether与if 均为"是否"的意思。 但在下列情况下，whether 不能被if 取代： 1. whether引导主语从句并在句首 2. 引导表语从句 3. whether从句作介词宾语 4. 从句后有"or not" Whether he will come is not clear. |