The forever force products series are not only complete in specification , but also enjoy the characteristics of reasonable structure , durable obdurability and reliable sealing etc 永力牌系列产品不仅规格齐全，而且具有合理的结构和坚固耐用、密封可靠等特点。
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Multilayer composite is a kind of obdurability material , which is imitative of the framework of shell in the nature . this kind composite is especially attractive because of its high toughness 叠层材料是人们模拟自然界贝壳的结构设计出的一种仿生结构强韧化的材料，由于具有较高的韧性而倍受关注。
