（2010）非周期信号的幅度频谱是：（） A.连续的 B.离散的，谱

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问题单项选择题

（2010）非周期信号的幅度频谱是：（）

A.连续的

B.离散的，谱线正负对称排列

C.跳变的

D.离散的，谱线均匀排列

答案

参考答案：A

解析：根据对模拟信号的频谱分析可知：周期信号的频谱是离散的，非周期信号的频谱是连续的。

句型转换

句型转换。

1. My mother got them yesterday from the post office.(改为一般疑问句)

_____ your mother _____ them yesterday from the post office?

2. I think they would come tonight. (改为否定句)

I _____ think they _____come tonight.

3. They are making birthday cards for Brian.(对划线部分提问)

What _____they _____for Brain?

4. My group's favorite subject is physical education. (对划线部分提问)

______ favorite subject ______physical education?

5. We have lived in this neighborhood for two years. (对划线部分提问)

______ ______have you lived in this neighborhood?

问答题

某变电站在一次倒闸操作时，值班负责人因故需短时离开，来不及审签操作票；于是，小王和小李先执行完操作任务后，立即找值班负责人进行补签。