Alex changed his mind at the last minute otherwise we an agreement.A. should have reached

问题补充：

Alex changed his mind at the last minute，otherwise we an agreement.

A. should have reached

B. could have reached

C. can reach

D. should reach

答案：

A. should have reached

(答案→)B. could have reached

C. can reach

D. should reach

解析：

句意为：亚历克斯最终改变了主意，否则的话我们就会达成一致了。对过去事情的推测，应该使用“情态动词＋have done”。should have done应该已经做了……；could have done很可能已经做了……。所以应该选择B项。