如图所示,两根相距为l的平行直导轨ab、cd、b、d间连有一固定电阻R,导轨电阻

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问题:

如图所示,两根相距为l的平行直导轨ab、cd、b、d间连有一固定电阻R,导轨电阻可忽略不计;MN为放在ab和cd上的一导体杆,与ab垂直,其电阻也为R;整个装置处于匀强磁场中,磁感应强度的大小为B,磁场方向垂直于导轨所在平面(指向图中纸面内);现对MN施力使它沿导轨方向以速度v(如图)做匀速运动;令U表示MN两端电压的大小,则(  )

A.U=vBl,流过固定电阻R的感应电流由b到d

B.U=vBl,流过固定电阻R的感应电流由d到b

C.U=vBl,流过固定电阻R的感应电流由b到d

D.U=vBl,流过固定电阻R的感应电流由d到b

考点:右手定则导体切割磁感线时的感应电动势
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有关慢性缩窄性心包炎的治疗,下列叙述哪项正确()。

A.内科保守治疗,静点心肌保护药物

B.一旦确诊应尽早手术治疗

C.强心利尿治疗

D.待肝肾功能正常时考虑手术治疗

E.彻底治疗原发病因

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微型载货汽车是指厂定最大总质量小于等于()。

A、3吨

B、1.8吨

C、4吨

D、2吨

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How much ______ these shorts?[ ]

A. is

B. are

C. has

D. have

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Passage One

When the television is good, nothing—not the theater, not the magazines, or newspapers—nothing is better. But when television is bad, nothing is worse. I invite you to sit down in front of your television set when your station goes on the air and stay there without a book, magazine, newspaper, or anything else to distract you and keep your eyes glued to that set until the station signs off. I can assure you that you will observe a vast wasteland. You will see a procession of game shows, violence, audience-participation shows, formula comedies about totally unbelievable families, blood and thunder, Mayhem, more violence, sadism, murder, Western badmen, Western goodmen, private eyes, Gangsters, still more violence, and cartoons. And endlessly, commercials that stream and cajole and offend. And most of all, boredom. True, you will see a few things you will enjoy. But they will be very, very few. And if you think I exaggerate, try it.

Is there no room on television to teach, to inform, to uplift, to stretch, to enlarge the capacities of our children Is there no room for programs to deepen the children’s understanding of children in other lands Is there no room for a children’s news show explaining something about the world for them at their level of understanding Is there no room for reading the great literature of the past, teaching them the great traditions of freedom There are some fine children’s shows, but they are drowned out in the massive doses of cartoons, violence, and more violence. Must these be your trademarks Search your conscience and see whether yon cannot offer more to your young beneficiaries whose future you guard so many hours each and every day.

There are many people in this great country, and you must serve all of us. You will get no argument from me if you say that, given a choice between a Western and a symphony, more people will watch the Western. I like Westerns and private eyes, too—but a steady diet for the whole country is obviously not in the public interest. We all know that people would more often prefer to be entertained than stimulated or informed. But your obligations are not satisfied if you look only to popularity as a test of what to broadcast. Yon are not only in show business: you are free to communicate ideas as well as to give relaxation. You must provide a wide range of choices, more diversity, more alternatives. It is not enough to cater to the nation’s whims—you must also serve the nation’s needs. The people own the air. They own it as much in prime evening time as they do at six o’clock in the morning. For every hour that the people give you—you own them something. I intend to see that your debt is paid with service.

It can be inferred from the passage in regard to television programming that the author believes ().

A.the broadcasters are trying to do the right thing but are failing

B.foreign countries are going to pattern their programs after ours

C.the listeners do not necessarily know what is good for them

D.six o’clock in the morning is too early for a television show

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生长激素缺乏症rhGH替代疗法的疗程是()

A.6个月

B.1年

C.5年

D.用至骨骺愈合为止

E.终身用药

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