what作引导词是什么从句

　　what引导从句用法例句

　　1.主语从句：What is beautiful is not always good.

　　美的东西并不总内是好的。

　　2.宾语从句：I could hardly believe what he had told me.

　　我简直不敢相信他所告诉我的。

　　3.表语从句：Books are what we need most.

　　书是容我们最需要的东西。

　　4.同位语从句：I have no idea what he is doing.

　　我不知道他正在做什么。