I think and the problem could be settled.A. If you don’t doubt your effortsB. So long a

问题补充：

, I think, and the problem could be settled.

A. If you don’t doubt your efforts

B. So long as you keep up your spirits

C. Making great efforts

D. A bit more efforts

答案：

A. If you don’t doubt your efforts

B. So long as you keep up your spirits

C. Making great efforts

(答案→)D. A bit more efforts

解析：考查祈使句。A bit more efforts 这里是祈使句，“只要再多一点努力”and这里是并列连词，用来连接另一句句子the problem could be settled soon，选D。