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问题 单项选择题

SDH的主要优点( )。

A．同步复用

B．标准光接口

C．强大的网络管理

D．以上都是

答案

参考答案：D

解析： 同步数字体系(SDH)，不仅仅适用于光纤，也适用于微波和卫星传输的通用性技术体制，而且使SDH在网络管理功能方面大大增强了。

填空题

根据句意和首字母或汉语提示完成单词

1. Peter borrowed my camera but he didn't r___________ it to me.

2. They had a very unusual e___________ on Sunday.

3. We all know Yang Liwei is a great a___________.

4. If you get a good c___________, ou must hold it.

5. When the alien was buying a s___________ the girl called the police.

6. Don't cross the street when the light is red. It is very ___________ (危险).

7. My spoken English is poor. I want to ___________(提高)it.

8. We must ___________(保护)the forest. It's good for us.

9. I don't like living ___________(独自).

10. I got up early this morning in ___________ to(为了)catch the early bus.
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选择题

下列原子结构示意图所表示的元素化学性质最稳定的是--------------------------(    )
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