2 . 选词填空。
1. He ________(must/might) get here in time ,but I can’t be sure.
2. He ________(can’t/mustn’t) have missed the train; he arrrived at the train station two hours early.
3. That must be a mistake. No, it ________(can’t/mustn’t) be a mistake.
4. Paul did a great job in the speech contest. He ________(must/can) have practised many times last week.
5. He ________(may/must) be at his office now, but you’d better make a phone to make sure.
6. Look, someone’s in the room. Who ________(can/must) it be ?
7. It ________(must have /may have) rained last night, for the ground is still wet.
8. I don’t know where she is, she ________(may/must) be in Wuhan.
9. With drones’ ability to see ahead, they ________(could/should ) signal any problem, so that fast -moving trains would be able to react in time.
10. I ________(needn’t/can’t) have bought so much wine -only two people came.

4 . There’s no such thing as a free lunch.
Things that are offered for free_________ have a hidden cost. (根据句意填空)