问题补充:
to find the book from the library, she decided to turn to her professor for help.
A. Failed
B. To fail
C. Having failed
D. Being failed
答案:
A. Failed
B. To fail
(答案→)C. Having failed
D. Being failed
解析:句意:从图书馆没有找到那本书,她决定向她的教授求助。现在分词作原因状语。上下文所
说的事情发生的时间显然有时间的先后。故要用现在分词的完成式=Because she had failed to find the book
from the library…