They don’t seem who for help.
A. know , to talk
B. know, to talk to
C. to know, to talk
D. to know, to talk to
网友回答
A. know , to talk
B. know, to talk to
C. to know, to talk
(答案→)D. to know, to talk to
解析：考查固定用法和不定式的用法。句意“他们似乎知道向谁求助。”seem to do sth.“好像要做某事”；疑问词+to do相当于疑问词引导的从句；talk to sb. for help“向某人求助”。故选D。