Question

The Chinese government has made it clear ______ it tries to achieve in space.为什么此处用what

为什么此处用what不用which？我认为他是一个定语从句，可此处用了what来作宾语从句，但是it已经是宾语，多用一个宾语从句不是赘余吗？

Answer 1

it 这里是形式宾语，它的实质内容是后面的从句。
The government has made it clear what it tries to achieve.
The government has made [what it(the government) tries to achieve] clear.
但习惯上只有第一句的用法被接受， 第二句只是为了解释，所以可见从句是句子的宾语。

类似形式主语的用法： It's clear what it tries to achieve.
也就是What it tries to achieve is clear.