71.When will you be through with your work, John?
本句中，be through ( with sb./sth.)意为“已结束”。本句相当于When will you finish your work?
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:
You can see the three people through the mist.透过薄雾，你能看见那三个人。
He will not live through tonight.他活不过今晚了。
It was through you that we were able to meet again.全仗你的帮助，我们才能重聚。