9 . 选词填空。
1. My mother is ill, so I ________(have to/ must)stay home to look after her.
2. He ________(can’t/ mustn’t)be Tom. Tom has gone to London, you know.
3. It’s dark outside. Besides, it’s raining heavily. So, you ________(had better/ might)go home with me.
4. In today’s information age, the loss of data ________(can/must)cause serious problems for a company.
5. It’s strange that he ________(should/ must)have taken the books without the owner’s permission.
6. Samuel, the tallest boy in our class, ________(can/should)easily reach the books on the top shelf.
7. My room is in a mess, but I ________(needn’t/ shouldn’t)clean it before I go out tonight. I can do it in the morning.

10 . 选词填空
1. He ____________(must/might) get here in time,   but I can’t be sure.
2. —How long ____________(may/must) I keep this book?
—You may keep it for two weeks.
3. He ____________ (can’t/mustn’t) have missed the train;   he arrived at the train station two hours early.
4. John, look at the time. ____________ (Must/Can) you play the piano at such a late hour?
5. She ____________(might/must) have achieved greater progress,   if you had given her more chances.
6. —That must be a mistake.
—No, it ____________ (can’t/mustn’t) be a mistake.
7. Paul did a great job in the speech contest. He ____________(must/can)have practised many times last week.
8. It is usually warm in my hometown in March, but it ____________(may/can)be rather cold sometimes.
9. I can make a lantern now,   but I ____________(can’t/couldn’t)when I was young.
10. —Can we go out and play football now?   
—No,   you ____________(can’t/mightn’t).