问题
选择题
Sheldon could have defeated Howard in the match, but he _______ too careless at the last minute.
A．is
B．was
C．has been
D．had been
答案
答案：B
题目分析： 句意：Sheldon本可以在比赛中打败 Howard的，但是他最后一分钟太粗心了。前面的could have defeated是对过去情况的虚拟，but后面的内容是过去的事实，用一般过去式，所以选B。