---who______it be that is knocking at the door?
---It_______be Father, but I’m not sure.
| A．can, must | B．can, may | C．must, can | D．may, must |
—Growing population resulted in growing rubbish.
—There is ______that rubbish will become the major threat to human beings in future.
| A．hope | B．afraid | C．possibility | D．likely |
—Happy birthday to you!
— ______.
| A．Happy birthday to you! | B．I am very glad． |
| C．That’s all right. | D．Thank you. |
— Have you read this book?
— Yes. But that one is ________ worth reading.
| A．best | B．more | C．much | D．better |
Maybe you have been to many countries, but nowhere else ___ such a beautiful palace.
| A．can you find | B．you could find |
| C．you can find | D．could you find |
—How are you getting on with your business?
—I'm glad to say it is ________.
| A．breaking up | B．taking up | C．turning up | D．picking up |