题干

如图所示,竖直平面内有一光滑绝缘半圆轨道,处于方向水平且与轨道平面平行的匀强电场中,轨道两端点A、C高度相同,与圆心O在同一水平线上,轨道的半径为R。一个质量为m的带正电的小球从槽右端的A处无初速地沿轨道下滑,滑到最低点B时对槽底的压力为2mg。则在小球的滑动过程中,有      (   )
   

A:小球到达B点时的速度为

B:小球到达B点时的速度为

C:小球在滑动过程中的最大速度为

D:小球在滑动过程中的最大速度为

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C

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    Four habits to help you succeed.

    We all want to succeed, whether it's in losing weight or learning to play the guitar. For those who have tried and failed, success seems difficult to understand.____

    Know your values.

    Finding your values is in line with creating motivation.____ Pick a handful of things and write them down. Remind yourself of your values every day and reflect on whether you are honoring those values through your work.

    Pick a goal and focus on it.

    Choose one goal to start something large enough that will give you a sense of achievement, while adjusting well to your values. Focus is key here.____ If you perform many tasks at a time, you might never finish your projects because they will take far too long.

    Set a time for success.

    Set a date for success. Know when you hope to realize your goal.____ By setting a time limit, you are making the process realistic.

    ____

    Failure can't be avoided when you take risks. By its very definition, the desire to succeed means you are risking failure. Many people tend to give up far too early. Don't fall into this trap! Remember your mindset earlier. Know it will happen. A failure is only you working out the details, and learning what works and what doesn't. Use failure. Treat it as a good thing, and go on.

A. The more focused you are on one goal, the higher chance you have of success.

B. Make the right decision.

C. I have made a list of four habits to help you set goals and realize them.

D. Don't give up because of failure.

E. Keep it realistic, while not giving you too much time.

F. Sit and reflect on what you value most.

D. Push yourself to be courageous, and take that next step.