—Howcouldyoumakesuchasillymistake?—I’msorry．I

问题详情：

— How could you make such a silly mistake?

— I’m sorry．I ______ it before I handed in the paper．

A．should check                                              B．could check

C．must have checked                                           D．ought to have checked

【回答】

D

知识点：虚拟语气

题型：选择题