7. We find it necessary ___________________ (将理论和实践结合起来). (combine)
8. You _________________ (本不该过着贫穷的生活). (ought)
v. 语法专练
A. ought to
1. He ought to help his brother work out the problem. (改成否定句)
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2.Tom ought to go to have a rest. (改成一般疑问句)
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3.Such things ought to be done at once, _____________?(反意问句)
B. 用must, have to, can, ought to, used to和be able to 的适当形式填空。
1. In some parts of the world, you ______boil the water before drinking it.
2. The bus caught fire seriously, but the passengers ¬¬¬¬______escape from it.
3. He ______have stayed at home this morning. I saw him shopping in another city.
4. You ______ smoke in this part of the hospital.
5. You ______keep a simple first aid box at home for any accidents.
6. If she is completely well, she ______be back at school today.
7. My father ______be a heavy smoker, but now he has given up the habit.
8. ------You ______have finished the article. The deadline is last Friday.
------Sorry. I have been busy these days. Could you give me 3 days more?
9. She ______ breathe, so I used the mouth-to-mouth way.
10. He ______have caught a bad cold last night, for his forehead felt burning.