阅读下面材料，按要求作文。

什么是幸福？不同的人有不同的体验。有人说：小时候，觉得幸福是一件实物；长大后，觉得幸福是一种状态；突然有一天，觉得幸福其实就是一种领悟。很多人追求一生，蓦然回首时才发现：幸福就是早上醒来有杯白开水放在床头，幸福原来如此简单。我们到底该如何把握幸福呢？

请你根据对这段文字的感悟，以“把握幸福”为题，写一篇不少于800字的文章。

要求：①立意自定；②除诗歌外，文体不限；③不得套作和抄袭；④书写规范，正确使用标点符号。

Networks can be interconnected by different devices. In the physical layer, networks can be connected by (11) or hubs, which just move the bits from one network to an identical network. One layer up we find bridges and switches, which operate at data link layer. They can accept (12) ,examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two networks. If two networks have (13) network layer, the router may be able to translate between the packer formats. In the transport layer we find transport gateway, which can interface between two transport connections. Finally, in the application layer, application gateways translate message (14) . As an example, gateways between Internet e-mail and X.400 e-mail must (15) the e-mail message and change various header fields.

12（）

A.frames

B.packets

C.packages

D.cells