B. 改错
　　1. We protested on vain. The government still insisted on
　　demolishing the building.
　　2. All he has done is vain. It won’t save our company.
　　3. It is absurd think about a plan that is impossible to implement.
　　4. Discipline can be relaxed until the last day of school has passed.
　　5. The country did not became a real democracy unless the middle
　　of last century.
　　6. It is with read books as with receiving education in social sciences.
　　7. It is with researching historic characters as with communicate with
　　persons of that time.
　　8. I thought it is with accepting the task as with putting it into
　　practice before I assimilated into the society.
　　9. It will be about half a year after you finish the engineering
　　construction supervision.
　　10.It will be about three years of getting to know each other
　　before they decided to marry.
　　【参考答案】
　　1. on―in 2. is―is in 3. think―thinking 4. can―cannot
　　5. unless―until 6. read―reading 7. communicate―communicating
　　8. is―was 9. after―before 10. will be―took

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