71.When will you be through with your work, John?

四级词汇讲解:
本句中，be through ( with sb./sth.)意为“已结束”。本句相当于When will you finish your work?

英语四级考点归纳：
与through有关的短语还有:through and through(完全，彻底)，get through(接通)，see through(看完)等。through本身的含义包括:

※ “穿过;贯穿”。如:
You can see the three people through the mist.透过薄雾，你能看见那三个人。

※ “自始至终”。如:
He will not live through tonight.他活不过今晚了。

※ “因为，凭借”。如:
It was through you that we were able to meet again.全仗你的帮助，我们才能重聚。