单项选择题
A. They are both regions of lowest loss.
B. They are both regions of low reflections.
C. They are both regions of low index of refraction.
D. They are both regions of low chromatic dispersion.
E. They are both regions of low Polarization Mode Dispersion （PMD）.
多项选择题 Whatthreeincombinationarefactorsthatcancausefour-wavemixinginfiber-opticcables？（）
单项选择题 Given the formula： （Fiber Attenuation * Km） + （Splice Attenuation * # of Splices） + （Connector Attenuation * # of Connectors） + （Optical Fiber or OADM） + Buffer（Fiber aging）） With regard to SONET/SDH optical calculations， what will the given formula provide？（）
单项选择题 Click the Exhibit button. Which type of multiplexer is shown in the exhibit？（）