Question

一个英语上的问题，烦请详解一下？

that the seas are being overfished has been known为什么不能改成the seas are being overfished that it has been known，但是却可以改成it has been known that the seas are being overfished

Answer 1

It has been known that the seas are being overfished. 众所周知，海洋正在被过度捕捞。

=That the seas are being overfished has been known

it是形式主语，真正主语是后面的主语从句that the seas are being overfished，has been known是现在完成时的被动语态，作谓语动词。

所以此句的句子结构完整正确。

再看这句：The seas are being overfished that it has been known. 其结构是错误的，什么句型也不是。

如果改成这样：The seas are being overfished，which has been known. 

这个句子就是对的了，which has been known这部分是定语从句，修饰前面的主句的，意思也没有发生改变。

英语句子，简单句或复合句，都必须要符合句型的构成规则的。

Answer 2

动名词的逻辑主语(理解与用法) 动名词的逻辑主语原则上是在动名词前用物主代词或名词所有格,但在口语中通常用宾格代词或名词普通格用作动名词的逻辑主语。
供参考