Don't go to open the door at once when the door bell _____.You should ask who it is at first.       [ ]

A. run off    

B. set off    

C. go off      

D. put off

我国民法的基本原则包括（）。

A.平等原则

B.诚实信用原则

C.强制原则

D.自愿原则

E.公序良俗原则