北京周口店地区房山岩体周围，分布有一套由片麻岩、斜长角闪岩、混合岩、糜棱岩等组成的变质杂岩。

In the area of Zhoukoudian, Beijing, there is a metamorphic complex compo-sed of gneiss, amphibolite migmatites and mylonites, along with the Fangshan intrusive body.

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齿轮倒棱机是对齿轮加工过程中形成的毛刺进行处理的设备。适用于加工各种直齿、斜齿、伞齿、链轮等齿形零件。

It is a burring equipment of machining gears, be the same with the tooth parts of spur gears, helical gears, bevel gears, chain wheel and so on.

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