—What do you think of your last trip?

—I had a very scary______in the mountains. I won’t go there again.

A．assistant

B．experience

C．station

D．souvenir

防火墙的NAT功能主要目的是（）。

A.进行入侵检测

B.隐藏内部网络IP地址及拓扑结构信息

C.防止病毒入侵

D.对应用层进行侦测和扫描