—Where did you get The Frog written by Mo Yan?

—I picked it up from a bookshop online if you ________ know.

A．must

B．will

C．can

D．shall

人防工程火灾危险性呈现（）的特点。

A.火场温度高，有毒气体多

B.内部格局复杂，疏散难度大

C.火灾蔓延迅速，早期发现困难

D.储存物品多，火灾荷载大

E.内部纵深大，灭火战斗困难