It can be inferred from the passage that

试卷相关题目

• 1CDs can last a long time if

  A.they are seldom used

  B.they play well and sound fine

  C.their users take good care of them

  D.they are developed with new technology

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• 2One of the differences between CD-RWs and CD-ROMs is

  A.CD-ROMs can be used for longer time

  B.CD-ROMs cannot be rewritten on

  C.CD-RWs hold more information

  D.CD-RWs are merely used for music recording

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• 3E-mail is mentioned in the third paragraph to show

  A.the variety of digital communications

  B.the development of new technologies

  C.the usefulness of digital codes

  D.the relationship between communication and technology

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• 4Music is recorded onto CDs as

  A.laser beams

  B.digital codes

  C.musical notes

  D.special sounds

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• 5It can be found from the last paragraph that infrasonic waves

  A.are harmless to people's health

  B.exist in people's internal organs

  C.can be used as deadly weapons

  D.can improve eyesight

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