题干

如图所示,一个带负电的油滴以水平向右的速度v进入一个方向垂直纸面向外的匀强磁场B后,保持原速度做匀速直线运动,如果使匀强磁场发生变化,则下列判断中错误的是(  )

A:磁场B减小,油滴动能增加

B:磁场B增大,油滴机械能不变

C:使磁场方向反向,油滴动能减小

D:使磁场方向反向后再减小,油滴重力势能减小

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C

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根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Fora lot of parents, sending their kids off to college is a bittersweetexperience. I think a lot of teenagers head to college without any idea abouthow money works. Don't let that happen to your college kid. Help themunderstand these issues before they step into that first class.

·Budget,budget, budget. ____ So start by making sure you understand budgeting and havebegun to use it as part of your financial plan.

·Independencemeans responsibility. Living away from home means you have to take care ofyourself. ____ Food doesn't just drop out of the sky, and gas doesn't magicallyappear in their car. Independence means responsibility.

·____Even if your kid is going to a small community college, they'll still probablyhave a few thousand dollars of tuition to pay. If you break it down, one classcan cost $1,000 at the very minimum! And that doesn't even include books.

·Choosea major wisely. ____ This isn't a must before they step on campus, but simplyplant a seed that gets them started thinking about what they want to do withtheir life. You don't want them graduating with a degree that leaves themunfulfilled or unable to find a job.

·Friendsmatter. ____ Who you hang out with definitely influences how you spend moneyand the decisions you make. Without being overbearing, remind them howimportant it is to have positive friends who build them up instead of bringingthem down.

Remember,as a parent, just be there for support and to streng then these principles throughouttheir college experience.

a.College isn't cheap.

b.Cherish your opportunity.

c.Help your teenager find his or herpassion.

d.However, not all friends can be reallydepended on.

e.New friends mean new opportunities andsocial situations.

f.Do your best to prepare your son ordaughter for what that means.

g.If you aren't using a budget, it'll bedifficult to convince your kid to use one.