These planets and their surfaces may be heavily modified by the last, big collision they experience (e.g. the largely metal composition of Mercury or the Moon).

这些行星最近所经历的大碰撞，会改变他们和他们的表面。

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The paper introduces the composition and the working axiom of rainbow metal roof's make-up machine, and the working axiom of the hydraulic system.

介绍了彩虹金属屋顶成型机的构成、工作原理，通过系统原理图介绍了液压驱动系统的组成、工作原理及特点。

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From the chemical composition, trace element, inoculation and thermal exchange of metal mold casting, the principle of chill formation and the effective methods for preventing chill were studied.

文章从铸铁的化学成分、微量元素、孕育处理及金属型的热交换方面叙述了产生白口的原理及防白口的有效方法。

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