该校园网内交换机数量较多，交换机间链路复杂，为了防止出现环路，需要在各交换机上运行______。
参考答案：生成树协议(STP)
I can help you with your English. --_____________.
A．You are a good man
B．You are so kind
C．That' s very kind of you
D．That' s right
As a child, I was told that the moon ___ no light of its own. I simply didn't believe it.
A．has
B．have
C．had
D．had had
