Scientists are convinced _____the positive effect of laughter _____physical and mental health．
| A．of ;on | B．by; in | C．of ; at | D．on ;at |
All her time ____________ her students, so she has no time for housework.
| A．devoted to teach | B．is devoted to teaching |
| C．is devoting to teaching | D．devoted to teaching |
With all teeth ____________, my grandfather has few choices on his diet.
| A．going out | B．staying out |
| C．working out | D．falling out |
A job in acting is becoming increasingly ____________ to young people.
| A．available | B．academic |
| C．attractive | D．energetic |
I don’t think Tom has passed the difficult exam, ____________?
| A．has he | B．don’t I |
| C．hasn’t he | D．do I |
In the end everything turns out OK—the teenager becomes ____________ healthy adult, and this period of change and challenge is traded for ____________ changes and challenges of grown-up life.
| A．a; / | B．the; / |
| C．a; the | D．the; the |