油浸纸绝缘多芯电力电缆的最小弯曲半径20倍于电缆外径。（）
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How is a Thin Film filter fabricated？ （）
A. The glass core is doped with an Erbium in periodic segments of the fiber.
B. Layers of high index ？and low index ？material are deposited on a glass substrate.
C. Thin layers of silica glass are placed onto wafers to produce a prism-like effect.
D. Fiber is etched with an ultraviolet laser that is precisely spaced for specific wavelength filtering.
消费者在购买、使用商品时，享有人身、财产安全不受损害的权利。
A. 正确
B. 错误
沥青混合料组成设计的目标是什么？它们之间存在哪些矛盾？
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