质量为m的带正电小球由空中某点自由下落,下落高度h后在空间加上竖直向上的匀强电场

题型:多选题

问题:

质量为m的带正电小球由空中某点自由下落,下落高度h后在空间加上竖直向上的匀强电场,再经过相同时间小球又回到原出发点,不计空气阻力,且整个运动过程中小球从未落地.重力加速度为g.则(  )

A.从加电场开始到小球返回原出发点的过程中,小球电势能减少了2mgh

B.从加电场开始到小球下落最低点的过程中,小球动能减少了 mgh

C.从开始下落到小球运动至最低点的过程中,小球重力势能减少了

4
3
mgh

D.小球返回原出发点时的速度大小为

8gh

考点:机械能守恒定律电势能
题型:多选题

某商城将化妆品和护肤护发品组成成套化妆品销售,应该按照化妆品的税率从高计算征收消费税。()

题型:多选题

下列各组物质中,前者为单质,后者为混合物的是(  )

A.铜、二氧化碳

B.铁粉、加碘食盐

C.氯化钾、洁净的空气

D.红磷、冰水混合物

题型:多选题

在330kV输变电工程管理中,监理项目部依据业主项目部的工程进度计划编制()报业主项目部审批。

A.施工进度计划

B.一级网络计划

C.二级网络计划

D.开工报审表

题型:多选题

The world is filled with smart, talented, educated and gifted people.We meet them every day A few days ago, my car was not running well.I pulled it in to a garage and the young mechanic had it fixed in just a few minutes.He knew what was wrong by simply listening to the engine.I was amazed.The sad truth is that great talent is not enough.

 I am constantly shocked at how little talented people earn. I heard the other day that less than 5 percent of Americans earn more than $100,000 a year. A business consultant who specializes in1 the medical trade was telling me how many doctors and dentists struggle financially. It was this business consultant who gave me the phrase, “They are one skill away from great wealth.”

There is an old saying that goes, "Job means 'just over broke(破产)’".And unfortunately, I would say that the saying applies to millions of people.Because schools do not think financial intelligence is intelligence, most workers "live within their means".They work and they pay the bills.Instead I recommend to young people to seek work for what they will learn, more than what they will earn.

When I ask the classes I teach, “How many of you can cook a better hamburger than McDonald's?” almost all the students raise their hands. I then ask, “So if most of you can cook a better hamburger, how come McDonald's makes more money than you?” The answer is obvious: McDonald's is excellent at business systems. The world is filled with talented poor people. They focus on perfecting their skills at building a better hamburger rather than the skills of selling and delivering the hamburger.

小题1:The author mentions the mechanic in the first paragraph to show that      

A.he is just one of the talented people

B.he is ready to help others

C.he has a sharp sense of hearing

D.he knows little about car repairing小题2:The underlined part in the third paragraph can be best replaced by____   

A.spend more than they can afford

B.do in their own way

C.1ive in their own circle

D.1ive within what they earn小题3:Why do talented people earn so little according to the author?

A.They don’t work hard enough

B.They lack financial intelligence.

C.They don't make full use of their talents

D.They have no specialized skills.小题4:The main purpose of the author is to tell us____      

A.how young people can find a satisfactory job

B.What schools should teach about finance

C.why so many talented people are poor

D.how McDonald's makes much money

题型:多选题

Tip-Edge直丝弓矫治技术的主要原理()

A.与Begg矫治器完全一致

B.与Begg矫治器一致,又具有edgewise系统的许多优点

C.与edgewise矫治器一致

D.与直丝弓矫治器一致

E.与自锁矫治器一致

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