15.　 She ___ have studied for yesterday's test, but she didn't.　　

14.　 John's score on the test is the highest in the class; he____ have studied hard last night.　

13.　 Let us play basketball, ______?　　

12.　 Let's clean our classroom, _____?　

11.　 The plant is dead. I _____ have given it more water.　

10. I _____ play football than baseball.　

9.　 Put on more clothes. You _____ be feeling cold with only a shirt on.　

8.　　　 ---"Must we do it now?"

---"No, you _____."　

7.　　　 The little girl _____ go there alone.　

6.　　　 Most of the students felt rather disappointed at the English party. They say that it ______ have been better organized.