分层限时跟踪练
Ⅰ.单句语法填空
1．I am puzzled(puzzle)by his failure to reply that he hasn't replied to my letter.
2．It was said that this was the only copy of the book in existence(exist)．
3．As we all know，a bad eating habit is harmful(harm) to one's health.
4．Unlike(like)what he said，he didn't carry out his promise.
5．As the old saying goes，it is easier to_pull(pull) down than to build up.
6．Give Mary a call；she needs cheering up.
