Because at least one asteroid appears to be coated by a thin layer of ice. And just that kind of asteroidal frosting could have been the source of our water here on Earth.
至少有一个行星被一层薄薄的冰层覆盖，这些冰可能就是地球上水的来源。
Low temperature hot water floor radiant heating system consists of heat source, and the collector, the heat insulation layer, heating pipe, pipeline, valve, filling layer and filter etc...
低温热水地面辐射供暖系统由热源，分、集水器，绝热层，加热管，填充层以及管路、阀门、过滤器等组成。
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