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【单选题】
以下关于光纤纤芯和包层折射率的说法哪个是错误的? Which is wrong with the fiber fiber core and the envelope refractive index?A.
普通光纤要保证信息传输纤芯折射率要大与包层折射率。 In order to ensure the information transmission, the refractive index of ordinary fiber core is larger than that of cladding.
B.
光纤中最外层包层的折射率最小。 The outermost cladding has the smallest refractive index in a double-clad fiber.
C.
三角芯光纤纤芯的折射率分布呈三角形。 The refractive index distribution of triangle core is triangular.
D.
椭圆芯光纤纤芯呈椭圆形可以保持信号光传输过程中的偏振态。 The elliptical core can maintain the polarization state in the process of signal light transmission.
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举一反三
【简答题】Listen to the material of Section C of Part 3, and complete Exercise C in Page 123-124. Then copy the answers to the blanks below. _____
【简答题】Listen to the material of Section D of Part 3, and complete Exercise D in Page 124. Then copy the answers to the blanks below. --What will banks and offices do on New Year's Day? --They will _____ ___...
【单选题】高血压的诊断标准中血压值应当为下列
A.
收缩压≥140mmHg和（或）舒张压≤90mmHg
B.
收缩压≤140mmHg和（或）舒张压≥90mmHg
C.
收缩压≤140mmHg和（或）舒张压≤90mmHg
D.
收缩压≥140mmHg和（或）舒张压≥90mmHg
E.
以上都不对
【简答题】Listen to the audio and fill in the blanks.(page 124)
【单选题】高血压的诊断标准中血压值应当为下列哪一项?
A.
收缩压≥140mmHg 和(或)舒张压≤90mmHg
B.
收缩压≤140mmHg 和(或)舒张压≥90mmHg
C.
收缩压≤140mmHg 和(或)舒张压≤90mmHg
D.
收缩压≥140mmHg 和(或)舒张压≥90mmHg
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