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问题 计算题

如图所示中质量为m的带电小球用绝缘线悬挂于O点，并处在水平向左的匀强电场中，场强为E，球静止时丝线与垂直夹角为，求：

小题1:小球带何种电荷，电量是多少？

小题2:若烧断丝线，则小球将作什么运动？（设电场范围足够大）

答案

小题1:正电荷  Eq=mgtanθ

小题2:作匀加速直线运动

完形填空

先通读下面的短文，掌握其大意，然后根据短文内容和所给首字母，在空格内填入一个适当的词，使短文意思完整。所填单词在题后横线上必须完整写出。

Do you always agree with your teacher? Sometimes you might have a different a  小题1:  to a Maths problem. Or maybe they scold(责备) you when you don’t think you did anything w 小题2: .

What do you do then? A story on sina.com said that more and more students choose to s   小题3:   out and sometimes even shout(喊叫) at their teachers.

It’s i   小题4: for students to say what they think. In the past, few Chinese students dared(敢于) to speak d  小题5:  to their teacher. It was an unwritten rule(不成文的规定) that what the teachers said is always right. But now students are b 小题6:  to think more of themselves and dare to say what they think right.

But students should choose the right way to speak out. We should respect(尊重) teachers. They are older than you and know more things. So, never use i 小题7:  words when speaking to them. And don’t make them u 小题8:   when you don’t agree with them.

Try to find the right time to talk to your teacher. For e  小题9: , talk about the problem after class.

R  小题10:  to talk about it in a friendly way.
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单项选择题

下列物质爆炸危险性最高的是（）

A、汽油 

B、乙炔 

C、苯
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