将下面每组中的两个句子合并，将其中一个改为状语从句。
(as long as, on condition that, lest, so…that, such…that, in case, as if, now that, whether…or, however, )
1) You’ve bought a new car.
What are you going to do with the old one?
2) We’d better take the telescope with us.
Perhaps it is needed.
3) We must hurry off.
Otherwise, we might miss the bus.
4) The problem was very complicated.
It took us nearly two weeks to solve it.
5) The aircraft was flying at a very high altitude.
We could hardly see it.
6) I’ll lend you my computer.
The condition is that you keep it in good shape.
7) You can go out.
But you should promise to be back before 11 at night.
8) I remember the whole thing.
It seems that it happened yesterday.
9) He tried very hard.
But he could not do the job satisfactorily.
10) It may take an hour or even a whole day.
But I shall find out the answer.
（三） 复杂的简单句
并列句和复合句往往可以浓缩成复杂的简单句，使语言更为紧凑、多样。
1. 表示时间、让步或条件的状语从句往往可以改写为介词词组作状语。
1) They looked both ways before they crossed the street.
2) I made my decision after I talked to Sir Francis.
3) Although he was ill, he was determined to carry out his plan.
4) Although they’re intelligent, they aren’t doing well in school.