______the library for hours without finding anything useful, I turned to my professor for help.

admin2018-03-28  41

问题 ______the library for hours without finding anything useful, I turned to my professor for help.

选项 A、To search
B、Having searched
C、Have searched
D、Searching

答案B

解析 考查现在分词的完成时。表示其动作在谓语动词的动作之前完成,作时间或原因状语,找资料是发生在寻求帮助之前,用having seacrched,故选B。
转载请注明原文地址:https://kaotiyun.com/show/kkaK777K
0

随机试题
最新回复(0)