Scientists are convinced the positive effect of laughter_____physical and mental health.
| A．of, at | B．by, in | C．of, on | D．on, at |
—that he picked up French?
—It was in 1949 he traveled in France.
| A．Was it when; that | B．When was it; that |
| C．Was it when; when | D．When was it; when |
Jack _______ yet, otherwise he would have telephoned me．
| A．mustn’t have arrived | B．shouldn’t have arrived |
| C．can’t have arrived | D．need not have arrived |
Niagara Fall is a great tourist _______ , drawing millions of visitors every year.
| A．attention | B．attraction | C．appointment | D．arrangement |
--- The weather has been very hot and dry.
--- Yes. If it had rained even a drop, things would be much better now! And my vegetables
then.
| A．wouldn’t die | B．didn’t die |
| C．hadn’t died | D．wouldn’t have died |
--- The research is difficult. Who do you think can do the job?
--- my students have a try?
| A．Will | B．Shall | C．Must | D．May |