. When your parents haven’t ____your letter for a long time,they will worry about you.
| A．heard | B．heard from | C．received | D．accepted |
—In case anyone ________ come in my absence, tell him I will be back soon.
—Sure, I will.
| A．would | B．should |
| C．will | D．shall |
John ________ yet, or he would have telephoned me.
| A．mustn't have arrived | B．shouldn't have arrived |
| C．needn't have arrived | D．can't have arrived |
—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 |
A survey has shown that 40% of those killed in traffic accidents ________ if they had been wearing seat belts.
| A．should have been saved |
| B．must have been saved |
| C．need have been saved |
| D．could have been saved |
—The research on the new flu virus vaccine is challenging and demanding.Who do you think can do the job?
—________ my students have a try?
| A．May | B．Must |
| C．Will | D．Shall |