不属于VPN的核心技术是（）。
A.隧道技术
B.身份认证
C.日志记录
D.访问控制
参考答案：C
We _____ the top of the mountain but for this awful weather. It rained all day. [ ]
A. will reach
B. would reach
C. have reached
D. would have reached
信息化战争中，（）成为部队战斗力的核心要素
A.信息
B.信息系统
C.信息化武器装备
D.制信息权
