I believe he has come这句话为什么可以不用that引导？什么时候必须用that呢？

来源：百度知道 编辑：UC知道 时间：2024/07/02 06:24:57

在宾语从句中,that口语中经常省略的.如:I know (that)He has come back.
that 在句中只是引导宾语从句的引导词,如果做了其他成分,就不能省略了.

先行词是指定语从句而言的.如: I don't know the man who /that spoke to me just now. that 即可以指人也可以指事 .定语从句中,that作宾语时,可以省略.如:I had seen the film (that)he told me .