21. The prisoner was ______ of his civil liberty for three years.

　　A) discharged

　　B) derived

　　C) deprived

　　D) dispatched

　　22. Small farms and the lack of modern technology have ______ agricultural production.

　　A) blundered

　　B) tangled

　　C) bewildered

　　D) hampered

　　23. The Japanese scientists have found that scents ______ efficiency and reduce stress among office workers.

　　A) enhance

　　B) amplilf

　　C) foster

　　D) magnify

　　24. All the students have to ______to the rules and regulations of the school.

　　A) confirm

　　B) confront

　　C) confine

　　D) conform

　　25. He ______ his head, wondering how to solve the problem.

　　A) scrapped

　　B) screwed

　　C) scraped

　　D) scratched

　　26. As soon as the boy was able to earn his own living he ______ his parents' strict rules.

　　A) defied

　　B) refuted

　　C) excluded

　　D) vetoed

　　27. The helicopter _____ a light plane and both pilots were killed.

　　A) coincided with

　　B) stumbled on

　　C) tumbled to

　　D) collided with

　　28. To ______ is to save and protect, to leave what we ourselves enjoy in such good condition that others may also share the enjoyment.

　　A) conserve

　　B) conceive

　　C) convert

　　D) contrive

　　29. Put on dark glasses or the sun will ______ you and you won' t be able to see.

　　A) discern

　　B) distort

　　C) distract

　　D) dazzle

　　30. In ______ times human beings did not travel for pleasure but to find a more favourable climate.

　　A) prime

　　B) primitive

　　C) primary

　　D) preliminary