你说的应该是主语从句吧。
我经常迟到让我的老板很生气。
这个中文句子是:我经常迟到。在中文中,我们可以用句子做主语,但是在英文中,你是否可以说I am often late makes my boss angry 呢?
不可以,英文中句子不能做主语,为了让这个句子变得正确,我们必须将这个句子变成一个名词性成分,怎么做呢?就是在I am often late这个句子前面加上一个that:That I am often late makes my boss angry. 这就正确了。
那么这个句子是不是有点生疏呢?我们经常会用It来代替这个这么长的主语,变成It makes my boss angry that I am often late。
总结:
I am often late makes my boss angry (错)
That I am often late makes my boss angry. (对,不常用)
It makes my boss angry that I am often late. (对,常用)
中间那个句子就是that放在句首的用法,掌握了吗?
不妨把下面这个句子自己改正确看看:
The moon itself doesn't give off light is common sense. (错)