You must work hard,____ you will not learn English well.

A. if                         B. whether              C. otherwise        D. unless

We arrived at the station ____ the train had left.

A. after            B. before          C. since          D. when

Let's walk over ___the shop on the other side of the street.

A. in                         B. to                           C. under                D. by   

Something must be done to prevent our city ____ by thick smoke.

A. to be polluted      B. from polluting     C. from being polluted D. polluting

The teacher is busy ____ correcting papers.

A. for                    B.in                   C.on             D.of

It's very kind____ you to repair the bike ____ me.

A.for.for           B.of,of                           C.of,for                            D.for,of

No one helped me . I did it all         myself .

A．for             B．by              C．from              D．to

“Would you like tea _____ coffee？” “_____, thanks.”

    A. or, No                                                 B. and, Either

    C. or, Neither                                           D. and, Each

It has not been decided ____ they will leave.

A. why              B. when             C. which                 D. what

My name is Robert， most of my friends call me Bob for short．

A．then B．instead C．however D．but