______ environmental damage is done，it takes many years for the ecosystem to recover．
| A．Even if | B．If only |
| C．As if | D．Once |
—The woman biologist stayed in Africa studying wild animals for 13 years before she returned.
— Oh, dear! She _________ a lot of difficulties!
| A．may go through | B．might go through |
| C．ought to have gone through | D．must have gone through |
—Lucy doesn’t mind lending you her dictionary.
—She _________. I’ve already borrowed one.
| A．can’t | B．mustn’t | C．needn’t | D．shouldn’t |
—I’ve taken someone else’s green sweater by mistake.
—It _________ Harry’s. He always wears green.
| A．has to be | B．will be | C．mustn’t be | D．could be |
You ______ be tired –you’ve only been working for an hour.
| A．must not | B．won’t | C．can’t | D．may not |
I often see lights in that empty house. Do you think I _______ report it to the police ?
| A．should | B．may | C．will | D．can |