本发明公开了一种双层结构的牙膏包装袋。
The present invention discloses a toothpaste packaging bag with double-layer structure.
推导出了由左右手材料构成的双层结构的转移矩阵。
This paper derived the transfer matrix for the bilayer structure composed of left-handed and right-handed materials.
由于搭建安全原因，所以不鼓励搭建双层结构的展台。
Double story construction is not encouraged in this exhibition due to the safety reason.
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