一个物体相对于另一个物体的位置改变叫做机械运动，它是绝对的，_爱下问搜题

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问题选择题

一个物体相对于另一个物体的位置改变叫做机械运动，它是绝对的，而静止是相对的，在有云的夜晚，我们抬头望月，觉得月亮在云中穿行，这时选取的参考系是（　　）

A．月亮

B．地面

C．云

D．星

答案

参考系是研究运动时来当作参考的物体，是假定不动的．抬头望明月，觉得月亮在云中穿行，是月亮相对于云在运动，故参考系为云．选项ABD错误．C正确．

故选C．

填空题

单词拼写。

1. Women in ____ (一般来说) like to shop for new clothes.

2. Health care is one of the ____ (主要的) problems in our time.

3. My father ____ (使……了解) me the game of football.

4. I'm afraid it's not the proper way to ____ (接近) her.

5. Her opinion ____ (代表) that of the majority.

6. She knows very little English, which often leads to ____ (误解) when she visits London.

7. He's sorry for what he did and he has been ____ (惩罚) for it.

8. My friend and I have ____ (相似的) tastes in music.

9. The children were ____ (好奇的) about everything they saw at the exhibition hall.

10. She always has such a happy ____ (表情) on her face.

单项选择题

蒸汽锅炉一般（）至少排污一次。

A、每天

B、每班

C、每周

D、每月