下列词语中划线的字，每组读音都相同的是[ ]

A．①诘责　拮据　　②倔强　自强不息

B．①翘首　翘起　　②刊载　满载而归

C．①懊悔　教诲　　②涨红　水涨船高

D．①伫立　贮藏　　②薄弱　厚此薄彼

—The light in his office is still on. Do you know _______?

—To prepare for the material(材料) the meeting will need tomorrow, I think.

A．if he works hard

B．why he stays up so late

C．why is he so busy

D．when he will stop working