If the south had won the war what is now the United States divided into several countrie

问题补充：

If the south had won the war, what is now the United States divided into several countries.

A. will be

B. might have been

C. should be

D. must have been

答案：

A. will be

B. might have been

C. should be

(答案→)D. must have been

解析：虚拟语气，与过去事实相反用过去完成时态。