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：句意，再努力点，我认为，问题就可能被解决。If you don’t doubt your efforts如果你不怀疑你的努力So long as you keep up your spirits只要你振作精神Making great efforts作出努力A bit more efforts再努力点，根据题意，故选D。