总体参数真值与（）之间的差异称为误差。 A.个体参数值 B.样本

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问题单项选择题

总体参数真值与（）之间的差异称为误差。

A.个体参数值

B.样本估计值

C.总体方差

D.个体方差

答案

参考答案：B

解析：本题考查误差的概念。总体参数真值与样本估计值之间的差异称为误差。

阅读理解

阅读短文，选择正确的答案。

Zhang Peng's uncle lives in Hangzhou. Zhang Peng went there with his parents last Monday. They went

there by train. It was a long trip. He slept on the train. The next morning, he got to Hangzhou. His uncle went

to the train station to meet them. Zhang Peng played with his cousin. He ate good food there. He visited the

West Lake. It was beautiful. He took many pictures. He came back to Beijing yesterday.

1. Where did Zhang Peng go?

A. Beijing

B. Hangzhou

C. Jilin

2. When did he go?

A. Last Tuesday.

B. Last Friday.

C. Last Monday.

3. Did Zhang Peng go by train?

A. Yes, he did.

B. No, he didn't.

C. Yes, he does.

4. What did he do there?

A. He did many things there.

B. He only visited the West Lake.

C. He only ate good food.

问答题简答题

铁路信号应满足哪些条件？