51．How many new materials are mentioned in this passage?
　　[A]Two．
　　[B]Three． 
　　[C]Four． 
　　[D]Five．
　　52．Why does the author mention genetic engineering and computer science?
　　[A]To compare them with the new materials．
　　[B]To show the significance of the new materials on the future world．
　　[C]To compare the new materials with them．
　　[D]To explain his point．
　　53．Why is transition difficult?
　　[A]Because transition requires money and time．
　　[B]Because many manufacturers are unwilling to change their equipment．
　　[C]Because research on new materials is very difficult．
　　[D]Because it takes long time．
　　54．Where lies success of a country in the New Age of Super stuff?
　　[A]It lies in research．
　　[B]It lies in investment．
　　[C]It lies in innovation．
　　[D]It lies in application．
　　55．Why could not ceramics be used widely in the past?
　　[A]Because of their brittleness．
　　[B]Because people didn’t know how to use them．
　　[C]Because they were not useful．
　　[D]Because they could not resist heat．

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