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问题 计算题

一不计重力的带电粒子质量为m，电量为+q，经一电压为U1平板电容器C1加速后，沿平行板电容器C2两板的中轴进入C2，恰好从C2下边缘射出。C2两板间电压为U2，长为L，如图所示。求平行板电容器C2上下两极板间距离d=？

答案

根据动能定理可得，在偏转电场中有，，竖直方向，联立可得行板电容器C2上下两极板间距离d=

故答案为：

阅读理解

Do you know Marc Yu (余俊承). He is very famous . He is only nine years old. He is a Chinese American. His mother is from Macao. He likes music very much and he has great musical talent（天赋）. He can play forty pieces of classical music now.

After hearing Mary Had a little Lamb one time at the age of three, he began playing it on the piano. Before that, he didn’t learn the piano at all. He started to take the piano lessons at the age of three. His first public performance（表演） was at the age of three , too.

Now he can play great music for people on the stage. He wants to be a famous musician like Lang Lang in the future. He likes LangLang very much. Lang Lang is his idol.

小题1:How old is Marc Yu?

A．9

B．3

C．7

D．8小题2:Where is his mother from?

A．His mother is from America

B．His mother is from Macao

C．His mother is from Tai Wang

D．His mother is from Hong Kong小题3:When did he begin to learn the piano?

A．At the age of 9

B．At the age of 5

C．At the age of 3

D．At the age of 10小题4:.How many pieces of classical music can he play now?

A．14

B．4

C．40

D．400小题5:What does Lang Lang do?

A．A pop singer

B．A rock singer

C．A musician

D．A writer
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单项选择题

患儿，男，9岁，高热3天，头痛烦躁，口渴饮水，食欲不振，双侧腮部漫肿、胀痛、坚硬拒按，咀嚼困难，咽红肿痛，舌红苔黄，脉象滑数。治疗首选方剂为

A．普济消毒饮
B．清瘟败毒饮
C．白虎汤
D．黄连解毒汤
E．五味消毒饮
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