it was obvious that he was very embarrassed中为什么不用obviously?修饰句子不是该用副词吗?

题目

it was obvious that he was very embarrassed中为什么不用obviously?修饰句子不是该用副词吗?

答案

如果用obviously,就必须去掉it is - - - that.
It was obvious that he was very embarrassed.(主语从句)
=== Obviously,he was very embarrassed.（简单句）