It is impissible that he earns so much money only by selling books.该句是什么句型?

It is impissible that he earns so much money only by selling books.该句是什么句型?

您好：
这是that 引导的主语从句.
it 是形式主语, 真正的主语是he earns so much money only by selling books.
目的是避免主语过长,显得头重脚轻,保持句子平衡.
这句话可以改为：
He earns so much money only by selling books is impissible.

主语从句，真正的主语是he earns so much money only by selling books，it是形式主语

it + be+adj + that-从句
it做形式主语， that从句做真正主语
eg. It is important that we should learn English well.

主语从句

他通过卖书赚了这么多钱，真不可思议

It is (adj) that ... 这种都能算作“强调”句型，用 it 做形式主语，that 后面的从句才是真正主语。
其中 adj （形容词）可以有很多。下面几个是常见的：
essential
imperative
important
impossible
terrible