______, I think, and all the problems could be settled.
A.If you make more efforts
B.Making more efforts
C.A bit more effort
D.To have made more efforts
网友回答
C解析选C。句中有并列连词and，故应选择C项。其中名词短语相当于一个祈使句，完整的句子为：Make more efforts, I think, and all the problems could be settled.如选A , and要删去。