一个句子在另一个句子中充当宾语,这个句子就叫做宾语从句,. 比如:我知道他喜欢我. 知道,是主句的谓语,他喜欢我是一个句子,做了“知道”的宾语. 英语中,如果宾语从句是一个陈述句,而且不缺成分,就可以用that引导,此时that可以省略. I know (that)he loves me 如果宾语从句是特殊疑问句,那么就要选相应的特殊疑问词来引导这个句子,而且,整个宾语从句的语序都要陈述语序. I don't know when he can be back = when can he be back?i don't know. I don't know where he works 如果宾语从句是一般疑问句,就要用whether来引导 如:I dont know whether he loves him.其实就相当于does he love him?i don't know.