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问题 单项选择题 A1/A2型题

发热最常见的病因为（）

A.变态反应

B.感染性疾病

C.无菌性坏死组织吸收

D.内分泌代谢障碍

E.体温调节中枢功能失调

答案

参考答案：B

解析：发热的病因很多，临床上可分为感染性与非感染性两大类，而以前者多见。

问答题

如图所示(a)，M、N为中心开有小孔的平行板电容器的两极，相距D＝1 m，其右侧为垂直纸面向里的匀强磁场，磁感强度B＝1×10－3 T，磁场区域足够长，宽为d＝0.01 m；在极板M、N之间加有如图(b)所示的变电压(设N极电势高于M极时电压为正)。现有带负电粒子不断从极板M中央小孔处射入电容器内(粒子的初速度可看做为零，重力不计)，取其荷质比，问：

(1)在变交电压第一个周期内哪些时刻进入电容器内的粒子能从磁场的右侧射出来？

(2)若上述交变电压的周期可以变化，则其周期满足什么条件时，才能保证有带电粒从右侧射出来？
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填空题

根据句意和首字母补全单词。

1. We want some v _____ to help paint the house.

2. The soldier had a terrible w _____in his belly.

3. The little dog w _____  its tail with pleasure.

4. You'd better h _____ if you want to see him.

5. It is n _____ for old people to understand what they think and feel.

6. Mary  r _____  to the door when she heard the car.

7. Mrs. White gave b _____  to a fine healthy baby at her late thirties.

8. The policeman is looking for the o _____ of the dog.

9. You really b _____ quite well.

10. The old woman lives alone. She often feels l _____.
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