what或when在句子中间 出现表示什么

1.what [ (h)wɔt ] .
pron. 什么

eg：
Do you know what's on tonight?
你知道今天上演什么？

She is not what she was a few years ago.
她已经不是几年前的她了。

She certainly knows what's what.
她可知道都是怎么回事。

Girl: Yes, that s what he did.
女孩：是的，是这样子没错。

2.when [ (h)wen ] . .
conj. 当...时
pron.&ad. 什么时候

eg：
He was fond of drawing when he was a child.
他还是个孩子时就喜欢画画。

Turn off the switch when anything goes wrong with the machine.
如果机器出故障，就把开关关掉。

It was raining when we arrived.
我们到的时候正在下雨。

The Queen's last visit was in May, when she opened the new hospital.
女王上次来访是在五月份，她那时主持了这座医院的落成典礼。

He works when he might retire.
虽然可以退休，他还是工作。

What I wonder is when he left.
我想知道他是何时离开的。

从句咯！你去查查从句，就会发现他们充当的是连词