18.The climbers their ambition by reaching the summit of the mountain. A.obtained B.sustained C.maintained D.realized 19.The time has come we can make extensive use of nuclear energy. A.as B.while C.when D.since 20.Hardly the helicopter when the waiting crowd ran towards A.had.landed B.has.landed C.would.land D.was.landing 21.When products made in factories they are thrown away as garbage. A.come to an end B.are put to use C.are used up D.wear out 22.Mrs.Morris's daughter is pretty and and many girls envy her A.slender B.light C.faint D.minor 23.Last year,Mike earned his brother,though his brother has a better position. A.twice as many as B.twice as muchas C.twice than D.twice as more as 24.The professor had her her paper many times. A.rewritten B.to rewrite C.rewrite D.rewriting 25.Radar enables the pilot of an airliner.to take off.fly and land in A.danger B.comfort C.continuity D.safety18. The climbers their ambition by reaching the summit of the mountain. A. obtained B. sustained C. maintained D. realized 19. The time has come we can make extensive use of nuclear energy. A. as B. while C. when D. since 20. Hardly the helicopter when the waiting crowd ran towards it. A. had. landed B. has. landed C. would. land D. was.landing 21. When products made in factories they are thrown away as garbage. A. come to an end B. are put to use C. are used up D. wear out 22. Mrs. Morris's daughter is pretty and , and many girls envy her. A. slender B. light C. faint D. minor 23. Last year, Mike earned his brother, though his brother has a better position. ; A. twice as many as B. twice as much as C. twice than D. twice as more as 24. The professor had her her paper many times. A. rewritten B. to rewrite C. rewrite D. rewriting 25. Radar enables the pilot of an airliner. to take off. fly and land in A. danger B. comfort C. continuity D. safety