Don’t promise anything ______ you are one hundred percent sure.
| A．whether | B．after | C．how | D．unless |
_____ is the population of China? It is about 1,300,000,000.
| A．How many | B．How much | C．What | D．How |
Some doctors suggest that vinegar will ____ people from being infected ___ H1N1.
| A．protect; to | B．prevents; from | C．prevent; with | D．protect; in |
Our school is no longer ____ it was 10 years ago, _____ it was not well equipped.
| A．what, which | B．that , which | C．what, when | D．that, where |
He has been acting strangely these days. I can’t _____ his actions at all.
| A．account for | B．ask for | C．call for | D．stand for |
—Is Mary coming by plane?
—He should ,but he _____not. He likes traveling by train.
| A．must | B．can | C．need | D．may |