题干

下列图片中涉及许多物理知识的应用,其中正确的是

A:甲图中的指南针之所以指南是因为地磁场的南极在南方

B:乙图中的电磁起重机吊起很重的钢材是利用了电流的磁效应

C:丙图中的交流电动机是电磁感应现象的应用

D:丁图中的风力发电机的原理是磁场对电流的作用

上一题 下一题 0.0难度 选择题 更新时间:2017-02-28 03:04:06

答案(点此获取答案解析)

B

同类题3

阅读理解

    If you want to become a better reader, what should you know about speed of reading?

    Some people read very rapidly(快速地),while others read very slowly. But which one is better?

    The rapid reader may be a good reader when he reads a storybook for fun. But he may not be able to slow down enough to read directions carefully. He may read so rapidly that he does not take time to understand fully the ideas and information which are important to remember.

    The slow reader may be a good reader when he reads directions for making something. But he may spend too much time in reading a simple story which is meant to be enjoyed but is not important enough to be remembered.

    So, you see, either a rapid reader or a slow reader is not really a good one. If you wish to become a better reader, here are four important things to remember about speed of reading.

    1  Knowing why you are reading will often help you to know whether to read rapidly or slowly.

    2  Some things should be read slowly throughout. Examples are directions for making or doing something, science and history books, and Maths problems. You must read such things slowly or remember each important step and understand each important idea.

    3  Some things should be read rapidly throughout. Examples are simple stories for enjoyment, letters from friends and bits of news from hometown papers.

    4  In some of your reading, you must change your speed from fast to slow and slow to fast, as you go along. You will need to read certain pages rapidly and then slow down and do more careful reading when you come to important ideas.