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问题:

Which two statements are true about optical networ

选项

  • SONET and SDH both use time-division multiplexing.

  • An optical transport network system uses time-division multiplexing.

  • SONET and SDH both use wavelength-division multiplexing.

  • An optical transport network system uses wavelength-division multiplexing.

  • 答案:

    A,D