I would have gone to visit him in the hospital had it been at all possible, but I fully occupied the whole of last week.
A. were
B. had been
C. have been
D. was
网友回答
A. were
B. had been
C. have been
(答案→)D. was
解析：考查时态。I would have gone to visit him in the hospital had it been at all possible是含有虚拟语气的句子；but I fully occupied the whole of last week.是真实的情况，要用陈述语气，再根据时间状语last week，可知要用一般过去式。所以选D。