The teacher asked us________to do our homework．
A.didn't forget
B.not forget
C.not to forget
D.don't forget
网友回答
C解析分析：动词不定式的否定形式是not to do(如果是不带to的动词不定式，就是not do，如果要强调这种否定，也可以用never来代替not，成为never to do形式)，和动词谓语的否定结构是不同的(not总是放在谓语结构的第一个词的后面，如：am not，is not，were not，shall not，would not，have not，had not，does not，do not，did not等)。此处asked us to do结构，其否定形式应该是asked us not to do．