问题 选择题
如图所示,处在磁感应强度为B的匀强磁场中的单匝矩线圈abcd,以恒定的角速度ω绕ab边转动,磁场方向垂直于纸面向里,线圈所围面积为S,线圈导线的总电阻为R.t=0时刻线圈平面与纸面重合,且cd边正在离开纸面向外运动.则正确的是(  )

A.时刻t线圈中电流的瞬时值icosωt

B.线圈中电流的有效值I

C.线圈中电流的有效值I=

D.线圈消耗的电功率P

答案

答案:C

单项选择题 A1型题
阅读理解

Looking back on my childhood. I am convinced that naturalists are born and not made. Although we were brought up in the same way, my brothers and sisters soon  abandoned their pressed flowers and insects. Unlike them, I had no ear for music and languages. I was not an early reader and I could not do mental arithmetic.    

Before Word War I we spent our summer holidays in Hungary. I have only the dim memory of the house we lived in, of my room and my toys. Nor do I recall clearly the large  family of grandparents, aunts, uncles and cousins who gathered next door. But I do have a crystal clear memory of dogs, the farm animals, the local birds and above all, the insects.  

I am a naturalist, not a scientist. I have a strong love of the natural world, and my enthusiasm has led me into varied investigations. I love discussing my favorite topics and enjoy burning the midnight oil reading about other people’s observations and discoveries. Then something happens that brings these observations together in my conscious mind. Suddenly you fancy you see the answer to the riddle. Because it all seems to fit together .This has resulted in my publishing 300 papers and books. Which some may light honor, with the title of scientific research.  

But curiosity a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist? One of the outstanding and essential qualities required is self-discipline, a quality I lack. A scientist can be made a naturalist. If you can combine the two, you get the best of both worlds. 

小题1:According to the author, a born naturalist should first of all be _____

A.full of ambition

B.self-disciplined

C.full of enthusiasm

D.knowledgeable小题2:The first paragraph tells us that the author _____

A.lost his hearing when he was a child

B.didn’t like his brothers and sisters

C.was interested in flowers and insects in his childhood

D.was born to a naturalist’s family小题3:The author says that he is a naturalist rather than a scientist probably because he thinks he ____.

A.just rends about other peoples observations and discoveries.

B.Lacks some of the qualities required of scientist.

C.Has a great deal of trouble doing mental arithmetic.

D.Come up with solutions in most natural ways.小题4:The author can’t remember him relatives clearly because__

A.He didn’t live very long with them

B.He was too young when he lived with them.

C.The family was extremely large

D.He was fully occupied with observing nature.小题5:Which of the following statements is true?

A.The author believes that a born naturalist can not be scientist.

B.The author read a lot of books about the natural world and oil industry

C.The author’s brothers and sisters were good at music and languages.

D.The author spent a lot of time working on riddles.