— Why does the river smell terrible?
— Because large quantities of polluted water _______ into it.
| A．have poured | B．is being poured | C．has been poured | D．have been poured |
He paid for a seat, when he _________ have entered free.
| A．could | B．would | C．must | D．need |
—Do you know where David is? I couldn’t find him anywhere.
—Well. He _________have gone far—his coat’s still here.
| A．shouldn’t | B．mustn’t | C．can’t | D．wouldn’t |
Helen _________ go on the trip with us, but she isn’t quite sure yet.
| A．shall | B．must | C．may | D．can |
Mr. White _______ at 8:30 for the meeting, but he didn’t show up.
| A．should have arrived | B．should arrive |
| C．should have had arrived | D．should be arriving |
— Mum, I’ve been studying English since 8 o’clock. _______ I go out and play with tom for a while ?
— No, I’m afraid not. Besides, it’s raining outside now.
| A．Can’t | B．Wouldn’t | C．May not | D．Won’t |