Open back: Common style of case bound book . Also called Hollow back.

空背: 一般精装书籍均假定为空背,不用特别说明.

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Then two kinds of light - weighted mirrors with sandwich and open back structures were also compared.

根据计算结果比较了这几种材料的性能,最后比较了两种轻型反射镜结构—对称夹心结构和底面开口结构.

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Golden Week, Mount Emei, Jiuzhaigou, Dujiangyan scenic spots and other traditional open back to normal.

黄金周期间, 峨眉山 、 九寨沟 、 都江堰等传统景区恢复正常开放.

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