例句：
When did that happen?
那件事是什么時(shí)候發(fā)生的？
They stood respectfully when he entered the room.
當(dāng)他走進(jìn)房間時(shí)，他們都恭恭敬敬地站著。、
We waited while he dined.
他在吃飯，我們等他。
While you are up, close the door.
你要是起來就把門關(guān)上。
I must finish off this work while the light is good.
趁這會兒光線充足我必須把這項(xiàng)工作完成。