At proper horse races everyone has already studied the form of the horse .A. behind timeB.

问题补充：

At proper horse races everyone has already studied the form of the horse .

A. behind time

B. in progress

C. in advance

D. in time

答案：

A. behind time

B. in progress

C. in advance

D. in time

解析：考查词组辨析：. in progress在进行中， in advance提前， in time迟早，及时，句意是：在赛马比赛中，每个人已经提前对马的情况做了研究。选C。