We can never expect _______bluer sky unless we create ______ less polluted world.
| A．a；a | B．a；the | C．the；a | D．the；the |
Are you still here？ You ______ home hours ago.
| A．should go | B．should have gone |
| C．might go | D．may have gone |
As she’s not here, I suppose she _____ home.
| A．must go | B．must have gone |
| C．might go | D．might be going |
You _____ him the news; he knew it already.
| A．needn’t tell | B．needn’t have told |
| C．mightn’t tell | D．mightn’t have told |
You _____ practise the drums while the baby is sleeping.
| A．needn’t | B．mightn’t | C．mustn’t | D．won’t |
The police still haven’t found her, but they’re doing all they _____.
| A．may | B．can | C．must | D．will |