Question

宾语从句中，what怎么用，它跟that有什么区别

Answer 1

what、that均可引导宾语从句，what在从句中可做句子成分，而that 在从句中不做句子成分。

Answer 2

that：
陈述句做宾语从句时，用 that 连接，that 在句中没有实际意义，不能充当句子成分，口语中可以忽略
例句：I think (that) he will come at once.
what:
特殊疑问句做宾语从句时，用 what，when，who，which等引导
例句：I don't understand what he really wants.

Answer 3

that：
陈述句做宾语从句时，用 that 连接，that 在句中没有实际意义，不能充当句子成分，口语中可以忽略
例句：I think (that) he will come at once.
what:
特殊疑问句做宾语从句时，用 what，when，who，which等引导
例句：I don't understand what he really wants.