If you are careful enough you will make mistakes in your exams.A. mainlyB. seldomC. usua

问题补充：

If you are careful enough, you will make mistakes in your exams.

A. mainly

B. seldom

C. usually

D. probably

答案：

A. mainly

(答案→)B. seldom

C. usually

D. probably

解析：本题的含义是如果你足够认真的话，你将很少犯错误，seldom表示很少的意思，与题意相符，故本题选B。