选择题：I am ashamed ,sir,that I wasted the many hours __ I should have studied in class.
问题描述：
选择题：I am ashamed ,sir,that I wasted the many hours __ I should have studied in class.
A.whileB.as
C.once D.when
选D , 为什么?
答
选D
1、that后引导的先行词是the many hours,所以选D
2、四个选项中,D选项的when有转折的意思,如“虽然,然而,可是”的意思,句子的意思可被理解为“我当时应该认真学习的,而我却浪费了那些时间,感到很惭愧”,句中就应有转折的意思,所以选D（when).