—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 |
Nearly________ of the surface of our planet is covered by water.
| A．seven-ten | B．seven-tenth | C．seven-tenths | D．seventh-ten |
It’s said that __________ is going to give us a lecture.
| A．an American famous young | B．a famous American youg |
| C．a famous young American | D．a young famous American |
We had ___________ wonderful time_________the party_______ other day.
| A．a,on,the | B．/,at,on | C．a,at,the | D．/,on,/ |
I don't remember___________ to the airport that year.
| A．to be taken | B．being taken | C．having | D．to take |
A man does not know the difficulty of anything_________ he does it personally.
| A．although | B．if | C．because | D．unless |