大家好，欢迎来到IT知识分享网。

什么是主语从句

复合句中充当主语成分的句子。

主要有哪些词引导主语从句

从属连词：that whether
连接代词：who whoever whom whose what whatever which whichever
连接副词：when where how why whenever wherever however

主语从句的时态不受主句时态的影响和限制

That he finished writing the composition in such a short time surprised us all.
他在如此短的时间内写完作文使我们十分惊讶。
Whether we will go for an outing tomorrow remains unknown.
我们明天是否会去郊游仍旧未知。
Who will be our monitor hasn’t been decided yet.
现在还没有决定谁会成为我们的班长。
Whom we must study for is a question of great importance.
“我们为谁而学习”是个很重要的问题。
What caused the accident remains unknown.
事故的起因是未知的。
Whatever you did is right.
你做的任何事都是正确的。
Whom the watch belongs to is unknown.
手表的归属是未知的。
What we need is time.
我们需要的是时间。
What we need are good doctors.
我们需要的是好的医生。

it做形式主语

主语从句

总结

（1）连词位于句首不能省略；
（2）主语从句大多数情况下视为第三人称单数。