1．It was snowing when we got to the airport.
我们到达机场时，天正下着雪。
2．He had put the broken vase away before his mother came back.
他趁妈妈还没回来就把打碎的花瓶收拾好了。
3．He has written to me frequently since I got sick.
自从我病了以后，他经常给我写信。
4．Not until recently did I know what he had done.
直到最近我才知道他所做的事。
5．You will improve your oral English if you keep on practising.
如果你坚持练习的话，你将会提高你的英语口语。
6．Don't go out tomorrow morning in case Mr Li should come to visit you.
明天上午不要出去以防李先生会来拜访你。
7．However difficult (No matter how difficult) the work is，we will try our best to finish it in time.
无论工作多么困难，我们都要尽全力及时完成。
