II. 单项填空（共15小题；每小题1分, 满分15分）
从A、B、C、D四个选项中选出可以填入空白处的最佳答案。
11. —She looks very excited. She __________have won the first prize.
—I guess so. She is a born winner.
A. must B. could C. should D. might
12. Not __________the possible danger, Eric swam farther and farther.
A. realize B. realized C. to realize D. realizing
13. I find __________challenging to follow Professor Brown’s lecture.
A. this B. that C. it D. one
14. Yesterday I had a drink with my friends. I thought it was the best drink I __________in my life.
A. have enjoyed B. were enjoying C. would enjoy D. had enjoyed
15. He is __________a heart operation last year, and now he seems perfectly healthy.
A. said to receive B. said to have received
C. saying to receive D. saying to have received
16. —Would you please change my appointment with Mr. Li to 9 o’clock tomorrow?
—I am afraid he __________an important conference then. How about 11 o’clock?
