一、who 是代詞，可作疑問代詞、連接代詞和關系代詞。

作疑問代詞引導特殊疑問句。

例句：

Who are you looking for?

Who will help you?

作連接代詞引導名詞性從句。

The teacher asked us who could anster this question.

作關系代詞引導定語從句。

The man who said hello to you is Tom's brother.

二：wait是實義動詞，是不及物動詞。可獨立作謂語，當後面需要跟賓語時，常加介詞for,wait for sb./sth.

Mary is waiting for you at the gate.

三、when是副詞，可作疑問副詞、連接副詞和關系副詞。

作疑問副詞引導特殊疑問句。

When did you begin to go to school?

作連接副詞引導名詞性從句。

I don't know when they will leave.

作關系副詞引導定語從句。

This is the house where he lived.

詞類:

vt. 等候；推遲；延緩

vi. 等待；耽擱；伺候用餐

n. 等待；等候
I can't wait to check my grades.

我迫不及待地去查詢我的成績。

There's no point in your wait.

你的等待是沒有意義的。

He waited tables in this restaurant all summer vacation.

一整個暑假，他都在這個餐廳當服務員。

You can wait for the bus at the bus station.

你可以在汽車站等車。

The long wait for the doctor really made me anxious.

等醫生看病等了那麼長時間，真讓我焦急。

你應該問wait是什麼動詞，wait可做及物動詞，那麼後面就可以加名詞，名詞性從句，名詞性短語，只要意思OK你加什麼都可以。wait也可以做不及物動詞，所以只要意思OK你什麼都不加也可以。至於副詞是脩飾成分，加什麼對wait都沒影響。