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  3. The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is ha

The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is ha

admin2013-03-11  70
问题     The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to【S1】______what life would be like without them. When there is a【S2】______failure, people grope about in candlelight, cars【S3】______in the streets because there are no traffic lights to guide them, and food【S4】______in silent refrigerators.
    Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has【S5】______been experimenting in this field for million of years. Scientists are【S6】______more and more that the living world may hold many interesting secrets of electricity that could benefit humanity.
    All living cells send out tiny pulses of electricity. As the heart【S7】______, it sends out pulses of record; they form an electrocardiogram(心电图), which a doctor can study to determine how well the heart is working.  The brain, too, sends out brain【S8】______of electricity,  which can be recorded in an electroencephalogram(脑电图). The electric currents generated by most living cells are extremely small--often so small that【S9】______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 cells are linked together, the effects can be【S10】______.

A)spoils                                           I)apparently
B)sensitive                                        J)discovering
C)beats                                            K)reasonable
D)waves                                            L)power
E)astonishing                                      M)hits
F)seemingly                                        N)imagine
G)stop                                             O)hesitate
H)determine
【S3】
选项
答案O
解析 本分句缺少一个谓语动词。由because there are no traffic lights to guide them可知，是因为没有信号灯指示车辆，所以应该是车辆不知所措，hesitate符合本意。
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