—I have been waiting for you so long.
—Sorry, I have been in the library, _______ my friend look for some books.
A.helped
B.helping
C.to help
D.help
答案:B
考察非谓语动词,根据句子结构可知,此处为状语,help的逻辑主语是I,help与逻辑主语I之间是主动关系,即选择B。
—I have been waiting for you so long.
—Sorry, I have been in the library, _______ my friend look for some books.
A.helped
B.helping
C.to help
D.help
答案:B
考察非谓语动词,根据句子结构可知,此处为状语,help的逻辑主语是I,help与逻辑主语I之间是主动关系,即选择B。