各级人民政府在传染病防治工作中的主要预防措施包括()A．开展群众性卫生活动 B．进行

家用电冰箱及其原理电路图，如图所示。冰箱的压缩机由一个温控开关自动控制，冷藏室的照明灯由冰箱门进行控制。

（1）给冰箱提供电能的电源是_____ （选填“干电池”、“蓄电池”或“交流电源”），冰箱工作时，将电能转化为______ 能。

（2）日常生活经验表明，冰箱门打开时，照明灯亮，门控开关应处于_____ 状态，冰箱门关上时，照明灯熄，门控开关应处于______ 状态。

（3）比较冰箱甲、乙两种原理电路图，甲电路的特点是 _________________，乙电路的特点是 ______________________。

A thief returned a mobile phone and thousands of yuan he had stolen from a woman after receiving 21 text messages from her, a local newspaper reported.

Pan Aiying, a Chinese teacher at Wutou Middle School in Qihe County, in East China’s Shandong Province, didn’t think her text messages would help to get her belongings(财物) back.

A young man riding a motorcycle robbed her of her bag, in which there was her mobile phone, bank cards and 4,900 yuan, as she was riding her bicycle home on Saturday evening.

Pan said at first she considered calling the police, but then decided to try to persuade（说服）the young man to return her bag. Pan called her lost phone with her friend’s, but couldn’t get through. So she began sending messages.

“Hey, I’m Pan Aiying, a teacher from Wutou Middle School. You must be going through a difficult time. If so, I will not blame you.” Wrote Pan in her first text message, which got no answer. “Keep the 4,900 yuan if you really need it, but please return the other things to me. You are still young. To make mistakes is human. Correcting your mistake is more important than anything.” Pan wrote in another message.

She gave up hope after sending 21 text messages without any answer and planned to call the police the next morning. However, as she left her home on Sunday morning, Pan found her stolen bag lying in the courtyard. Nothing was lost.

“Pan: I am sorry. I made a mistake. Please forgive me. You are so kind even though I stole from you. I’ll correct my ways and be an honest person,” said a letter left with the bag.

1. Where was Pan Aiying robbed?

A. In the school.   B. At home.   C. In the courtyard.   D. on her way home

2. Why didn’t Pan Aiying call the police at first?

A. Because she thought the police wouldn’t help her.

B. Because it was too late at that time.

C. Because she wanted to communicate with the thief first.

D. Because her friend asked her not to.

3. How long was Pan Aiying’s bag missing?

A. About two days.                      B. About 12 hours.  

C. About one day and a half.               D. About 24 hours.

4. From the news we can learn that ____________.

A. the young man would not steal any more

B. Pan Aiying didn’t give up hope after sending 21 text messages

C. the young man would pay a visit to Pan Aiying personally

D. Pan Aiying teaches English in a middle school in Shandong Province

目视飞行

FDGJ并联的RC电路的作用是（）。

卸扣的横销受力产生变形时应报废。