A titanic impact could have stripped away a portion of its rocky mantle, leaving behind a metallic core whose density is out of proportion with the original ratio of rock to metal.

超大碰撞可能剥去了水星的一部分岩石地幔，留下了一个金属核心，其密度与原来的岩石与金属的比例相比大得不成比例。

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The gas cools off enough for the metal, rock and (far enough from the forming star) ice to condense out into tiny particles.

气体冷却到能够让金属、岩石和(离正在形成的星星足够远的)冰凝结成小微粒。

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So-called "heavy metal" rock is a good example of this.

那种所谓的“重金属”摇滚是个非常好的例子。

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The three-day festival features music by heavy metal, alternative rock and hip-hop bands.

VOA: special.2010.08.02

It mixes the sounds of hard punk and heavy metal rock and roll.

VOA: special.2009.11.06

The film satirizes the behaviour and musical pretensions of hard rock and metal bands.

BBC: Chris O'Dowd to star in Spinal Tap-style series on

Hard rock and metal have been Finland's most successful music export in recent years.

NPR: The Sounds of Finnish Musical Experiments

There's an important distinction between these two types of objects: Comets are mostly water, ice and dust, while asteroids are mostly rock or metal.

CNN: While you were working: An asteroid just flew by