If a coil has no metal core it has an air core.

如果线圈没有金属芯子，它就有一个空气芯子。

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Just name a few: metal core, industrial metal, classic rock and melodic death metal.

我说一些吧：硬核金属、工业金属、经典摇滚、旋律死亡金属。

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A method for forming the leading edge portion using refractory metal core technology is described.

对使用耐热金属芯工艺制出该翼面部的方法予以说明。

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Mr. Morell says he'll work out to any old-school rap or hard-core metal.

WSJ: Business Partners Double Up for Exercise

Well, we just got to see some prototypes of the device, including the basic CORE 2 band, its metal bracelet and swappable plastic face plate accessories, and learned a bit more about the device.

ENGADGET: BodyMedia CORE 2 armband and View patch health monitors hands-on

He recommends people get a solid or metal door for the front door and a solid-core door with a deadbolt for the master bedroom.

FORBES: Magazine Article