The importance of saving gas_______be stressed too much. Automobiles use up some 70 billion gallons of gas a year.
| A．can’t | B．mustn’t | C．shouldn’t | D．may not |
The research lacks evidence, and therefore, its conclusions are doubtful.
| A．solid | B．fierce | C．severe | D．potential |
We live in an age more information is available with greater ease than ever before.
| A．why | B．when | C．to whom | D．on which |
I think Tom, as the head of a big department, should either study regularly or______ his job.
| A．quits | B．to quit | C．quitting | D．quit |
Youras a student will be excellent if you develop a habit of reflecting on how you learn.
| A． | operation | B． | growth | C． | performance | D． | character |
all the animals I've ever had, these two dogs arc the most sensitive to the spoken word.
| A．From | B．Of | C．For | D．With |