He didn’t pass the final examination.He ______ it.
问题描述：
He didn’t pass the final examination.He ______ it.
选项:
a、must have prepared for
b、ought to prepare for
c、ought to have prepared for
d、ought to prepare for
答
选C
虚拟语气.
他没通过考试.他本该准备好的.（但他没有做）ought to have...本应该做.但没做