题目

    , I think, and all the problems could be settled. A. If you make more efforts B. Making more efforts C. A bit more effort D. To have made more efforts 答案：C 解析: 句中有并列连词and，故应择C项。其中名词短语相当于一个祈使句，完整的句子为：Make more efforts, I think, and all the problems could be settled.如A , and要删去。唐玄宗上台后，任用富于改革的房玄龄为相，励精图治，开创了一代繁荣盛世。