出国留学网2014年托福考试电力范文背诵

出国留学网专题频道2014年托福考试电力范文背诵栏目,提供与2014年托福考试电力范文背诵相关的所有资讯,希望我们所做的能让您感到满意!

2014年托福考试之电力范文背诵

 

  托福考试每年报考的人数基本都是在呈上升的趋势,根据历年的考试积累的经验也越来越多,为此出国留学网托福栏目为大家整理了《2014年托福考试之电力范文背诵》,供大家参考!

  2014年托福考试之电力范文背诵

  关于电

  The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flickering candlelight, cars hesitate in the streets because there are no traffic lights to guide them, and food spoils in silent refrigerators.

  Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has apparently been experimenting in this field for million of years. Scientists are discovering more and more that the living world may hold many interesting secrets of electricity that could benefit humanity.

  All living cell send out tiny pulses of electricity. As the heart beats, it sends out pulses of record; they form an electrocardiogram, which a doctor can study to determine how well the heart is working. The brain, too, sends out brain waves of electricity, which can be recorded in an electroencephalogram. The electric currents generated by most living cells are extremely small - often so small that sensitive instruments are needed to record them. But in some animals, certain muscle cells have become so specialized as electrical generators that they do not work as muscle cells at all. When large numbers of these cell are linked together, ...