阅读短文，从方框中选择适当的单词填空（每词限用一次）。

An old woman had a cat. The cat was very old. She could not run quickly, 小题1:_____she could not bite. One day the old cat saw a mouse. She jumped and caught the mouse. But she could not bite it, so the mouse got out of her mouth and ran小题2:_________.

Then the old woman became very 小题3:______because the cat had not killed the mouse. She began to hit the cat. The cat said, "Don’t hit your old 小题4:______. I have worked for you for many years, and I would work for you still, but I am too old. Do not be unkind 小题5:______ the old, but remember what good work the old did when they were young."

在一个办公室内，将6台计算机用1台交换机连接成网络，该网络的物理拓扑结构为（）。

A.星状

B.总线状

C.树状

D.环状