I think and the problem could be settled.A. So long as you keep up your spiritsB. A bit

问题补充：

, I think, and the problem could be settled.

A. So long as you keep up your spirits

B. A bit more effort

C. If you doubt your efforts

D. Making great efforts

答案：

A. So long as you keep up your spirits

(答案→)B. A bit more effort

C. If you doubt your efforts

D. Making great efforts

解析：考查固定句型：名词短语+and/or+简单句，句意是：再多点努力，问题就解决了，其他几个选项都是状语，和并列连词and不符。选B。