下面关于压缩模量的叙述错误的是（）。 A．压缩模量是通过室内试验测得的 B．压缩模量

解下列方程：

（1）x²-2x-1=0；

（2）（x-2）²+4x（x-2）=0。

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Networks can be interconnected by different devices．In the physical layer，networks can be connected by (66) or Hubs, which just move the bits from one network to an identical net-work. One layer up we find bridgas and swiehes, which operate at data link layer. They can accept (67) , 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 netwoks. If two networks have (68) network layer, the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which can interface between the two transport connections. Finally, in the application layer, application gateways translate message
(69) . As an example, gateways between Internet e-mail and X.400 e-mail must (70) the e-mail message and change various header fields.

A．analyze

B．pairs

C．delete

D．create

对于反应来说，以其反应速率的表示中，速率最快的是（   ）。

A．

B．

C．

D．无法比较

以太网的网卡地址如果用十六进制表示有（）位.

A、12

B、32

C、16

D、8