问题 选择题
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

答案

答案:A

选择题
阅读理解

阅读理解。

     I was wondering when it would happen. As everyone who lives in London and other cities

around Britain will know, urban foxes are now commonplace. I recently saw one in the middle

of the day, wandering along a street in Pimlico. Twenty years ago, that sight would have stopped

the traffic. Now, it is barely worth a remark. Foxes are large animals, as big as many dogs. Of

course, as in the terrifying incident at Homerton, one would attack a baby sooner or later.

    Actually, this has already happened. In 2002, at Dartford in Kent, a fox bit a 14-week-old boy

in the living room of the family home while his mother was sleeping. The last government preferred

to ignore the incident; it was, after all trying to ban foxhunting at the time. It could see that some folk

love urban foxes, perhaps having the same affection for wildlife as the people I have seen in London

parks feeding rats along with squirrels and ducks.

    The foxites even include animal scientists, who would seem to have persuaded Bristol City

Council (whose advisory Living with Urban Foxes has been adopted by the Chartered Institute

of Environmental Health) that foxes never attack humans. But then they also deny that country foxes

target lambs, when every hill farmer I know would tell them differently. A lamb is much the same

size as a baby. It is no more difficult to get into a house than into a hen cage.

    According to Living with Urban Foxes, “the fox population is stable”, and has not significantly

increased. Is this true? When I first lived in London in the late 1970s, urban foxes had an almost

mythical status. They were like yetis. You never saw one; you weren’t sure they really existed.

Now, they are part of the scene. I wouldn’t be surprised to find one. Friends in the suburbs are

plagued(困扰)with them. A study in Bristol showed that an astonishing 8 percent of pets caged

in gardens are killed by foxes each year.

    Surely, if foxes are now harming babies, it is time for something to be done about them, yet this is

not as straightforward as it might seem. While country residents refer to foxes as harmful animals,

that is not how they are officially classified; this means that local authorities do not have a statutory

obligation(法定的义务)to control them. It would be an easy thing for this government to change

the legislation.

1.What is the author’s purpose in writing the passage?

A. To urge the government to control urban foxes.

B. To show how to provide food for urban foxes.

C. To protect urban foxes from traffic accidents.

D. To prove urban foxes are not dangerous as expected.

2.The underlined word “foxites” in Paragraph 3 probably refers to those who ______.

A. hate urban foxes

B. love urban foxes

C. support foxhunting

D. oppose foxhunting

3.What is the author’s attitude toward Living with Urban Foxes?

A. Support.

B. Praise.

C. Disbelief.

D. Tolerance.

4.What kind of people is the author worried about most?

A. Farmers.

B. Students.

C. Drivers.

D. Babies.