影片《西安事变》中,蒋介石与周恩来互称“蒋校长”和“周主任”,源于他们曾共事于[ ]
A.北京大学
B.工农革命学校
C.京师大学堂
D.黄埔军校
答案:D
成本-效益分析是指
A.CUAB.CEAC.CBAD.CMAE.E-mail
Father advised me not to say anything until_____ at the meeting.
A.asking
B.to ask
C.asked
D.ask