执行周期性位臵更新时为了（）。
A、告诉网络MS的位臵
B、告诉网络MS还附着在网络上
C、寻呼MS
参考答案：B
I regret _____ hard at school, or I would have succeeded in passing the exam.
A．not to work
B．having not worked
C．to have not worked
D．not having worked
某主机的 IP 地址为 202.113.25.55，子网掩码为 255.255.255.240。该主机的有限广播地址为（ ）。
A． 202.113.25.255
B． 202.113.25.240
C． 255.255.255.55
D． 255.255.255.255
