sheath
核心词议：

速记方法
速记技巧 词源词根法 来自古英语sceath，套，护套，来自proto-Germanic*skaithiz，套，护套，来自PIE*skei，切，分开，词源同segment,section,science.比喻用法，即两块分开的木板，剑鞘的原型。

知识扩展
词组短语 leaf sheath叶鞘；tendon sheath[解]腱鞘

中文词源： sheath 剑鞘，套，护套 来自古英语 sceath,套，护套，来自 proto-Germanic*skaithiz,套，护套，来自 PIE*skei,切，分 开，词源同 segment,section,science.比喻用法，即两块分开的木板，剑鞘的原型。 sheath
精选例句

常见考点例句：

Its researchers have turned them into a type of cell that produces the insulating sheath around a nerve cell .

其研究人员已经把干细胞变成了一种在神经细胞周围产生绝缘护套的细胞。

Aerosol jet at first atomises nanoparticle-based print materials into microscopic droplets , which are then focused , using a sheath of gas , into a precise jet stream directed by a nozzle .

气溶胶喷气首先将基于纳米颗粒的印刷材料分裂成微小墨滴，随后这些墨滴在鞘中气体的作用下集中到由喷嘴控制的精确气流中。

Whenever there 's a nick or hairline crack in an insulation sheath , the electrical field in the underlying copper subtly shifts .

在绝缘套上只要出现缺口或者毛细裂缝，线缆里的铜周围的电场就会轻微改变。

Special kinds ofsteel , natural initial corrosion of the outer layer creates a protective sheath , that prevents the corrosion from advancing further into the bulk of the material , similarly as in the case of e.g. copper .

特殊材质的铁，最初在最外层生锈腐蚀而后产生一层保护鞘，可以防止腐蚀进一步扩大到大部分的材料上，这个情况跟铜腐蚀的情况差不多。

Despite its bad reputation , cholesterol is essential to life : it is a building block of the outer membrane of cells , and it is a principal ingredient in the digestive juice bile , in the fatty sheath that insulates nerves , and in sex hormones such as estrogen and androgen .

尽管名声不好，但是胆固醇确实是生活中不可缺少的一部分：它参与形成了细胞膜；是胆汁酸的主要成分；存在于隔绝叶脉的脂肪鞘里；还存在于雌激素和男性素这样的性激素里面。