— How do you find the book? 

—        

— I mean what do you think of the book.   -Oh,it's wonderful.    [ ]

A. Quite by accident.    

B. What do you mean by that?    

C. Mm, let me think.    

D. Once again?

风险评价是对系统存在的危险进行定性或定量的分析，得出系统发生危险的可能性及其后果（）的评价.

A、完好程序 

B、危险程度 

C、严重程度