如图所示,矩形线圈有N匝,长为a,宽为b,每匝线圈电阻为R,从磁感应强度为B的匀

题型:选择题

问题:

如图所示,矩形线圈有N匝,长为a,宽为b,每匝线圈电阻为R,从磁感应强度为B的匀强磁场中以速度v匀速拉出来,那么,产生的感应电动势和流经线圈中的感应电流的大小应为(  )

A.E=Bav,

B.E=NBav,

C.E=Bav,

D.E=NBav,

考点:导体切割磁感线时的感应电动势闭合电路欧姆定律
题型:选择题

阅读理解。

                                                      Bicycles in China

     Bicycles are very popular in China. In our country you can see bicycles almost everywhere. When you

walk on the road, you will find a lot of people riding bicycles to school, shops and anywhere else. Therefore

(因此), China is known as "the kingdom of bicycles". In China, many families have one or two bicycles.

     Compared (与……比) with cars, bicycles have many advantages. First, they are much cheaper than cars.

Most Chinese can't afford cars, but they can afford bicycles. Second, bicycles are small enough to park

anywhere, while cars need a larger piece of land to park. What's more, with lower speed, bicycles are safer

than cars.

     However, bicycles also bring some problems. Some riders don't obey the traffic rules and some riders

don't think about others' safety. So they ride too fast. During rush hours, too many bicycles may cause traffic

jams. We still have a long way to go to solve the problem.

1. Where can you see bicycles in China?

A. In the big city.

B. In the town.

C. In the country.

D. Almost everywhere.

3. "The kingdom of bicycles" here is saying  ______.

A. China has a large number of bicycles

B. China makes bicycles

C. bicycles are a kingdom

D. only China has bicycles

3. Which of the following is NOT an advantage of bicycles?

A. Bicycles are much cheaper than cars.

B. Bicycles are easy to park.

C. Bicycles are more beautiful than cars.

D. Bicycles are safer than cars.

4. What problems can bicycles bring?

A. Bicycles are more and more expensive.

B. Riding bicycles is more dangerous than driving cars.

C. There are no places for so many bicycles.

D. Too many bicycles may cause traffic jams.

5. What does the last sentence mean?

A. We should drive cars instead of riding bicycles.

B. It's too far to ride bicycles.

C. Bicycles are safe enough.

D. We still need to do much to solve the problem.

题型:选择题

关于家庭治疗的基本原理叙述错误的是()

A.症状往往出现于持续展开着的家庭生活周期发生变化、中断之时

B.系统思维重视环境对个体的影响,同时强调人际互动中的个体对情境的整体认知和评价

C.家庭治疗主要把人当作"黑箱"来对待,注重刺激与反应之间的简单关系

D.患者的病态并不仅仅是内在的生物学因素构成的因果链条的最后一环,而是各种内因与外因之间互动关系的过程性、动态性表现

E.系统式家庭治疗师与结构式家庭治疗师在关于"正常家庭"的观念上存在分歧

题型:选择题

下列城市中,属于我国特别行政区的是[ ]

A、香港

B、深圳

C、广州

D、珠海

题型:选择题

3岁左右,幼儿已经能够掌握()个词。

题型:选择题

质量m=2kg的物体以50J的初动能在粗糙的水平面上滑行,其动能与位移关系如图所示,则物体所受阻力Ff为______N,物体在水平面上滑行的时间t为______s.

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