题干

在光滑的绝缘水平面上,相隔2L的A、B两点固定有两个电荷量均为Q的正点电荷,a、O、b是A、B连线上的三点,O为中点,Oa=Ob=
L
2
。一质量为m、电荷量为q的试探电荷以初速度v0从a点出发沿A、B连线向B运动,在运动过程中,除静电力外,试探电荷受到一个大小恒定的阻力作用,当它运动到O点时,动能为初动能的2倍,到b点时速度刚好为零。已知静电力常量为k,设O处电势为零,求:
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阅读下面短文,根据短文内容,从短文后各题所给的A、B、C、D四个选项中,选择最佳选项。

    The town of Pressure and the town of Pleasure were neighbors but they had nothing in common. Residents(居民) built walls to 1 influence from the other town.

    In Pressure, everyone wanted to be the very best. When women gave birth, they would compete(竞争、比赛) to have the baby with the loudest cry. There was violent competition in every aspect(方面) of life. Because 2 was the symbol(象征) of success. People were always busy making money, with no time for relaxation. Some young people couldn't bear the intensity(紧张) and chose to drink to escape(逃避).

    In Pleasure, the motto(格言) was: If only you like it, do it. People grew up without pressure and could do anything they liked. Children played computer games day and night. At school, teachers didn't care 3 students came or not. Workers might sit around the office all day long drinking coffee and doing 4 .Thanks to the lack(缺乏) of regulations(规章制度), nobody worried about losing their jobs. It was pleasure that mattered. The computers they used were old ones from the town of Pressure.

    Some of the young were addicted(上瘾) to drugs(药物)5 the emptiness(空虚) of their lives. Then, people in the two towns began asking themselves, “What is life 6 ?” But, just before life in the two towns completely7, there came a great person—Mr Reason. He went from door to door, talking with people and 8 advice. People in Pressure learnt to be satisfied with what they had 9 people in Pleasure began to make plans. They 10 the walls between them and built a road to connect the two.