A Frenchman who lost his arms and legs successfully swam across the Channel a challenge h

问题补充：

A Frenchman who lost his arms and legs successfully swam across the Channel, a challenge he for two years.

A. has been preparing

B. had been preparing

C. has prepared

D. prepares

答案：

A. has been preparing

(答案→)B. had been preparing

C. has prepared

D. prepares

解析：这题考查现在完成进行时的用法：现在完成进行时表示过去到现在一直在进行的动作，句意是：一个失去膀子和腿的法国人成功的游过了海峡，这是他准备了两年的挑战。选B。