30. How long do you think it will be _____ we can find a new water source?
| A．after | B．before | C．when | D．Since |
—Is it good to look up every new word when I come across it in reading?
—No, you ________， because you are likely to guess the meaning from the context.
| A．don't have to | B．shouldn't |
| C．can't A | D．mustn't |
—Please don't tell anybody.
—I ________. I promise.
| A．can't | B．don't |
| C．won't | D．mustn't |
To make the most of your time, live every moment as if it________ your last.
| A．is | B．would be |
| C．were | D．has been |
When my father is upset, he would rather ________.
| A．leave alone | B．we left him alone |
| C．left alone | D．we leave him alone |
What a pity! Considering his ability and experience, he ________ better.
| A．need have done | B．must have done |
| C．can have done | D．might have done |