I think and the problems could be settled .A. If you double you effortsB. So long as yo

问题补充：

,I think , and the problems could be settled .

A. If you double you efforts

B. So long as you keep up your spirts

C. Making greater efforts

D. A bit more efforts

答案：

A. If you double you efforts

B. So long as you keep up your spirts

C. Making greater efforts

(答案→)D. A bit more efforts

解析：名词+and+句子