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(huì)兒光線充足我必須把這項(xiàng)工作完成。