The flu is believed _________ by viruses that like to reproduce in the cells inside the human nose and throat.
| A．causing | B．being caused | C．to be caused | D．be have caused |
-She looks very happy. She __________ have passed the exam.
-I guess so. It's not difficult after all.
| A．should |
| B．must |
| C．could |
| D．might |
-Mother, I climbed up to that tall tree and picked this big apple.
-Jesus ！ You __________ down and hurt yourself.
| A．might have fallen |
| B．might fall |
| C．must have fallen |
| D．must fall |
-We expected you yesterday.
-I'm sorry, I __________ you to say that I couldn't be here until today.
| A．must have called |
| B．would be calling |
| C．could have called |
| D．should have called |
We lost our way in that small village, otherwise we __________ more places of interest yesterday.
| A．visited |
| B．had visited |
| C．would visit |
| D．would have visited |
We __________ have bought so much food now that Suzie won't be with us for dinner.
| A．may not |
| B．needn't |
| C．can't |
| D．mustn't |