根据短文内容及所给首字母填写所缺单词

     Many people find exams a frightening experience.Sitting down for an exam when everybody is so q   1   and serious

makes most people nervous.

     But there are a few things you can do to r  2     before you start. At the beginning of an exam,read all the instructions c  3     ,so you know exactly what you have to do. Work out how much time you can spend on each q   4   . If you feel

yourself getting nervous at any time,stop w   5   you are doing and take a few deep breaths.

     However,the most useful things are always done b   6   you get to the exam room. You may do some practice tests

and review your l  7     right way. And then the real thing will seem much e   8   .

     You also need to remember that exams are not the most important things in the world-even though you f  9     ,and

that you can do better next time.

1. _____ 2. _____  3. _____ 4. _____ 5. _____ 6. _____ 7. _____ 8. _____ 9. _____

以下关于网络体系结构的描述中，错误的是______。

A．网络体系结构是抽象的，而实现是具体的

B．层次结构的各层之间相对独立

C．网络体系结构对实现所规定功能的硬件和软件有明确的定义

D．当任何一层发生变化时，只要接口保持不变，其他各层均不受影响