3 . Every one of us ______ always breathe the same breath and share the same future as the people.

A．might

B．should

C．could

7 . In science, facts should be proved by experiments and research, and we ______ always believe everything we read and hear -- even if it is a great story.

A．can not

B．may not

C．must not

D．should not

9 . 格林一家也许已经预料到将发生的事。他们在一周前搬进城里了。
The Greens ________ what would happen. They moved to the city a week ago.

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).