问题
选择题
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
答案：B
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。