问题
选择题
_________, I think, and the problems would be settled.
A．If you double your efforts
B．Making more efforts
C．So long as you don’t lose heart
D．A bit more effort
答案
答案：D
根据句中的连词and可知此空缺少祈使句，如果没有and则A、C两个选项都正确。句意：我认为努力些问题就会解决。