系统管理员应该采用哪些安全措施？（）
A. 把root密码告诉每一位用户
B. 设置Telnet服务来提供远程系统维护
C. 经常检测帐户数量、内存信息和磁盘信息
D. 当员工辞职后，立刻删除该用户帐户
—_____ he ____ his lunch?— Yes, he did.
A. Does ,has
B. Does, have
C. Did, have
Did, had
—Did the thieves _____ into the car?—No, they______.
A. fell, didn’t
B. fall(落下), did
C. jump（跳）, didn’t
D. jump, did
-When did May come back from Hong Kong?-She __ from Hong Kong last Friday.
A. come back
B. comes back
C. returned back
D. came back
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