安装焊机空载自动断电保护装置的目的是（）A、避免焊工接触到带

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问题单项选择题

安装焊机空载自动断电保护装置的目的是（）

A、避免焊工接触到带电外壳而发生触事故

B、避免焊工在操作时接触二次回路的导体而发生触事故

C、避免焊工更换焊条时接触二次回路带电体而发生触事故

答案

参考答案：C

填空题

根据首字母提示填空完成句子。

1. H____________ is she going to get there? By train or by bus?

2. I b____________ some presents on my holiday.

3. Do you like h____________?

4. I'm r____________ a storybook.

5. My friend a____________ good food on his holiday.

6. I'm going back to C____________ next month.

7. She likes drawing p____________.

8. I often go to s____________ on foot.

9. I w____________ to the zoo yesterday.

10. He likes p____________ football.

单项选择题

在心室肌细胞动作电位，L型钙通道大量开放的时相是

A．1期
B．2期
C．3期
D．4期