X.800安全框架主要包括:安全攻击、安全机制和安全______。
参考答案:服务
解析:考察对X.800的了解。
If you ______ the chat room ten minutes ago, you _______ what we were talking about.
A.have joined ; will know
B.had joined ; would have known
C.should join ; would know
D.would join ; have known
《原野》中的地主形象是()。