单选题They peasants did what&nb

问题补充：

单选题Theypeasantsdidwhatthey____thecrops,butfailed.A.could saveB.could savingC.could to saveD.could saved

答案：

C解析考查句子结构。从句what they could(do)作动词did的宾语，不定式to save the crops作全句的目的状语。防止误选A.