1、由that引导的宾语从句,that无词义,通常可省略。例句:I know (that) he is Lily’s father.例句:She doesn’t know (that) she is ill.
注意事项:当主句的谓语动词是:suppose、think、expect、believe等词时,同时宾语从句表达的是否定的意思,那么需要把否定放置到主句位置表示。例句:I don’t think he will go to Beijing with me.
2、由whether、if引导的宾语从句,意思是“是否”。例句:Do you know whether/if he will come here?例句:I wonder whether/if he will come to my party.
特殊情况:只能用whether不能用if引导的宾语从句
(1)与or not连用时。例句:Do you know whether he will come here or not?
(2)与不定式to do连用时。例句:I don’t decide whether to go to the library.
(3)在介词的后面。例句:It depends on whether it will rain tomorrow.
3、由who、whom、whose、which、what、when、where、why、how等引导的宾语从句。例句:I know where he was born.