I don' t think Xiao Li is ____ the other students ____ mathematics.

A. after, on        B. after, with C. behind, in     D. behind, at

The accident is reported to have occurred __________ the first Sunday in February.

      A. at                B. on                C. in                   D. to

___ he has finished writing the novel is unknown. 

A. If                                  B. Whether                     C. When                         D. While

___ he did it remains a secret.            

A. What       B. Whom       C. Which       D. How

The scientist is well known us his great achievement．

A．to；for B．by；for C．by；as D．to；in

We didn’t live together. We kept in touch _______ writing often.

A. with    B. of  C. on     D. by

He ran off____ I could stop him.

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

They had camped once before, ____ they knew what to take.

A. because         B. now          C. so              D. since

Go ____ the gate and you' 11 find the entrance ____ the park ____ the other side.

A. through; to; on B. along ;of; on  C. down; to; at     D. up; of; by

He is running ____ the wind towards the east of the station ____ Tom is running ____ the right.

A. down; and; on B. against; while; on C.for;with;in     D. with; while; to