He spent too much time talking on ______ phone while we were all busy at _____ work.

A. the; /                             B. a; /                               C. /; /                         D. the; the

--- Must I turn off the gas after cooking?   --- Of course. You can never be ___ careful with that.

A. enough                    B. too                 C. so                  D. very

If _____ carefully, the experiment will be successful.?

A. do                               B. does                      C. done                     D. doing?

My friend Mary is _____ beautiful girl and _____ girl everyone likes to work with.?

A. a, a                           B. a, the                  C. the, a                       D. the, the?

According to the rules, students must not _____ their books during examinations.?

A. read　                                B. watch   ?            C. notice　                       D. look at

Who would you rather ______ you repair your CD player?

A. help                             B. helped                   C. helping                         D. to help

____ he will come or not is still unknown.     

A. If                  B. Where            C. That            D. Whether

I thought he hated the TV .You are right,____ he still watches the program.

A. yet             B. besides       C. also              D. then

The train leaves at 6:00 p.m. So I have to be at the station ____5:40p.m.at the latest.

A. until               B. after                     C. by                             D. around   

 51. He looked quite healthy ____ he was ____ the age of seventy.

A. when; at         B. because; in             C. if; for                  D. though; at