网络拓扑是指网络上设备之间连接的几何表示，典型的网络拓扑包括：总线型、环形、树形、网状型，以及目前局域网中常用的（）拓扑。
参考答案：星
根据提示补全句子。
1. My b_____________ is S_____________ 4th.
2. Lily often _____________ (go) to bed at 9: 00.
3. When is _____________ (she) birthday?
4. I often go _____________ (shop) with my mother.
5. I like s_____________ best, because it's warm and sunny.
6. I'm _____________ (make) a birthday chart.
为防止可燃气体从压缩机轴封窜出，先用密封气封住密封油，再用密封油封住裂解气。
