a single word can change the meaning of a sentence, a single sentence can change the meaning of a paragraph.
| A．Just as | B．Even though |
| C．Until | D．Unless |
. It is usually warm in my hometown in March, but it _________ be rather cold sometimes.
| A．must | B．can |
| C．should | D．would |
. —What do you think we can do for our aged parents?
—You __________ do anything except to be with them and be yourself.
| A．don’t have to | B．oughtn’t to |
| C．mustn’t | D．can’t |
. — My cat’s really fat.
— You __________ have given her so much food.
| A．wouldn’t | B．couldn’t |
| C．shouldn’t | D．mustn’t |
. — What does the sign over there read?
—“No person __________ smoke or carry a lighted cigarette，cigar or pipe in this area.”
| A．will | B．may |
| C．shall | D．must |
. I told your friend how to get to the hotel, but perhaps I __________ have driven her there.
| A．could | B．must |
| C．might | D．should |