• 2021-04-14 问题

    The central wavelengths of three low loss windows commonly used in optical fiber communication are ( ), ( ) and ( ). 光纤通信中常用的三个低损耗窗口的中心波长分别是()、()和()

    The central wavelengths of three low loss windows commonly used in optical fiber communication are ( ), ( ) and ( ). 光纤通信中常用的三个低损耗窗口的中心波长分别是()、()和()

  • 2022-06-03 问题

    Which is NOT the correct description about Laser? A: It stands for Light Amplification by Stimulated Emission. B: It’s a beam of light energy. C: All the light waves in a laser are emitted in the same rhythm. D: The light waves in a laser are of different wavelengths.

    Which is NOT the correct description about Laser? A: It stands for Light Amplification by Stimulated Emission. B: It’s a beam of light energy. C: All the light waves in a laser are emitted in the same rhythm. D: The light waves in a laser are of different wavelengths.

  • 2022-06-07 问题

    Why is more earth's heat blocked from escaping with more carbon dioxide in the atmosphere A: Carbon dioxide prevents the sun's energy from going back into space. B: Carbon dioxide radiates the sun's energy onto the earth. C: Carbon dioxide produces more heat in the atmosphere. D: Carbon dioxide takes in the sun's energy at infra-red wavelengths.

    Why is more earth's heat blocked from escaping with more carbon dioxide in the atmosphere A: Carbon dioxide prevents the sun's energy from going back into space. B: Carbon dioxide radiates the sun's energy onto the earth. C: Carbon dioxide produces more heat in the atmosphere. D: Carbon dioxide takes in the sun's energy at infra-red wavelengths.

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