用所给词的适当形式填空 1. Please listen to me (careful), I have something important to tell you. 2. The ( twelve) lesson is more difficult. 3. The girl is old enough to look after ( she). 4. The supermarket is usually _________ (crowd) on Sundays. 5. A cup is used for ___________(drink) water. 6. Lily is (help). He often helps others. 7. I think the most useful (invent) is the telephone. 8. How many (factory) are there in our country? 9. Though you failed this time, don't give up______ (study) . 10. I am afraid to hurt their __ ___ (feel).