路由器的发展表现在从基于软件实现路由功能的单总线CPU结构路由器，转向于基于硬件专用 ASIC芯片的路由交换的高性能的______。
A．交换路由器
B．算法
C．路由网关
D．Ethemet交换机
参考答案：A
解析：[知识点] 网络互联技术与互联设备
[评析] 改进传统网络的方法主要是：增大带宽与改进协议。增大带宽可以从传输介质和路由器性能两个方面着手。路由器是IP网络中的核心设备。路由器的硬件体系结构的发展经历了单总线单CPU、单总线主从CPU、单总线对称多CPU、多总线多CPU和交换结构5个发展阶段。这种发展从产品上集中表现在从基于软件实现路由功能的单总线单CPU结构的路由器，转向基于硬件专用的ASIC芯片的路由交换功能的高性能的交换路由器发展。
| When you first drift off into slumber, your eyes will roll about a bit, your temperature will drop slightly, your muscles will relax, and your breathing will become quite regular. Your brain waves slow down a bit, with the alpha rhythm predominating for the first few minutes. This is the first stage of sleep. For the next 30 minutes or so, you will drift down through Stage 2 and Stage 3. The lower your stage of sleep, the slower your brain waves will be. About 40-60 minutes after you lose consciousness, you will reach the last stage. Your brain waves will show the delta rhythm. You may think that you stay at this deep stage all the rest of the night, but that turns out not to be the case. About 80 minutes after you fall into slumber, your activity cycle will increase slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart around under your closed eyelids. This period of Rapid Eye Movements lasts for 8-15 minutes and is called REM sleep. During both light and deep sleep, the muscles in your body are relaxed but capable of movement. As you slip into REM sleep, a very odd thing occurs -- most of the voluntary muscles in your body become paralyzed. Although your brain shows very rapid bursts of neural activity during REM sleep, your body is incapable of moving. REM sleep is accompanied by extensive muscular inhibition. |
The best title for this passage would be______.
A．Brain Waves
B．Sleep Cycles
C．Daily Activities
D．Body Activities