— What ________ it be?     

— It can't be a mail box, for it's moving. It ________ be a car.     [      ]

A. must; must    

B. can; can      

C. can; must    

D. must; can

中古时期，适用于官僚贵族减免刑罚的特权原则有（）

A.八议

B.官当

C.上请

D.重罪十条