在全局开启GVRP后，则交换机上所有端口的GVRP都被自动开启。（）
参考答案：错
What did Dave do().
A.He lost his temper for no reason at all.
B.He left without saying a word.
C.He suddenly slipped and fell.
D.He suddenly fainted.
焦点到镜头中心的距离是该镜头的（）。
A、焦距
B、物距
C、像距
D、视场角
