If It had been possible I would have helped him but I too busy the.A. had beenB. would

问题补充：

If It had been possible, I would have helped him, but I too busy the.

A. had been

B. would be

C. were

D. was

答案：

A. had been

B. would be

C. were

(答案→)D. was

解析：前面是一个与过去事实相反的虚拟语气，but引导的真实情况。