如图所示,在竖直平面的坐标系xOy内,放置一个半径为R的圆形轨道(图中虚线),其

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问题:

如图所示,在竖直平面的坐标系xOy内,放置一个半径为R的圆形轨道(图中虚线),其圆心在x轴上,轨道内侧上的P点在y轴上,且OP=。现将一小球自P点水平抛出,要让小球再次到达轨道,并且有最大位移,不计空气阻力,重力加速度为g,则被抛小球的初速度大小是

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D.

考点:平抛运动
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“Hi,howareya.” some people say when they see a familiar face.The words run together into a mass,all sense and meaning lost. All the same,people do care how you are.After they greet you,it’s likely you will greet them back,with an equally meaningless phrase like,“Can’t complain,can’t complain.”You could probably complain,at length,or share a brilliant thought you were just beginning when a greeting interrupted you.You don’t though,you say,“Great,you?”

You are not giving each other information about your health and well­being.All the same,you are sharing information.You’re acknowledging each other’s positions as acknowledged friends,or at least as accepted acquaintances.And you are reestablishing the ties that may have lapsed(衰退) since yesterday,when you last met at the elevator or the entrance to the train station.

It’s what anthropologist(人类学家) Bronislaw Malinoski called a phatic(交流感情的) communication.Its message is not in the words you use,but in the fact that you speak ritually(仪式上地) accepted words.In Asia,for example,people may ask one another if they have eaten,or if they are busy.They’re not really asking for their lunch menu or their agenda,they are saying hello.A phatic signal merely says, “I see you there.” It says hi.

There’s embarrassment of being near people without acknowledging them.That uncomfortable feeling is one reason why lonely passengers in the subway may behave as if they cannot see anyone around them or may escape their uncomfortable situation with a book.Some people read all the way home,and never turn a page.

Your friend isn’t asking how you are,and you aren’t telling him.However,he is recognizing your existence,and when you answer,you are recognizing his.In addition,the set speech you have shared opens the door to closer communications if both agree.Someday,you may come to real close friendship,and really tell one another how you are.

Meanwhile,people who greet one another this way do care.They care enough to recognize someone’s essential humanity(人性).They send a signal across the space between,to share,very briefly and lightly,in awareness of one another.

Your greetings prove that neither of you has become a social outcast.How are you?You are still a member of society in good status.You are still the one who knows the rituals and secret passwords necessary to get to work each day.

小题1:When people greet,they ________.

A.want to show their different educational backgrounds

B.show nothing related with the words themselves

C.want to know other people’s privacy

D.express something special小题2:According to Bronislaw Malinoski,a phatic communication ________.

A.is rarely used by Asian people

B.is too complex to be used often

C.helps establish or keep certain relationships

D.often ruins the normal relationships between friends or acquaintances小题3:Some people seldom greet strangers because ________.

A.they want to be polite to others

B.they feel uncomfortable to do it

C.they don’t know when to greet them

D.they want to do something meaningful小题4:What does the text mainly tell us?

A.Greetings should be given better expressions.

B.Greetings convey different meanings to different people.

C.Greetings help prove an individual’s social independence.

D.Greetings help an individual be connected with the society.

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下列药物通过生物膜的转运机制需要载体的是()

A.被动扩散

B.主动转运

C.胞饮扩散

D.吞噬作用

E.膜孔转运

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我国赋予外国人或外国组织的赔偿请求权,是无条件的或绝对的。

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引入HSDPA后,不但可以提高峰值数据速率和减少延迟,还可以增加小区的容量。这主要是由于采用下面的哪些关键技术?()

A.采用2ms的短帧

B.在物理层采用HARQ和AMC等链路自适应技术

C.引入高阶调制提高频谱利用率

D.采用功率控制

E.通过码分和时分在各个UE之间灵活调度

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有限责任公司和股份有限公司,都是股份制企业,都叫公司,只在名称上小有不同而己。

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