英文文法一問，句字插入的..... , ____ , ....?

在句中插入說話者的判斷，評論，情緒，或註解等時(有時只是口頭蟬)，所用的文字與原句的句構無關，有時還會對語氣有加強或緩和的作用：

Nevertheless, the radioactive materials used in nuclear power would, in fact, cause even more far-reaching environmental problems.
這裡的in fact有強調的作用，表示所言為事實而非理論(in theory)。

They use many known arts like Chinese opera or raffiti as evidence to support their arguments which, however, I deem as inappropriate.
這裡的however是讓我的看法跟他們的作法形成對照關係，同時也有緩和語氣及轉折的功能。但刪去however後，並不改變句義。

一些有插入語的例句如下：
Most, if not all, of this report was written by Ms. Wang.
Things are different now, you know.
He wsa really afraid, I believe.
My mother, whom I'm sure you remember, passed away last year.
He was, it appears, in poor health.
What do you think is your biggest fault? (do you think是插入語)

He (was) really afraid,however,(adv)in whatever way or degree.