Put drainage material such as sand or rock dust in the path area.

在路径区域放置排水材料，如沙子或岩粉。

Comprised of rock, dust, gases and ice, comets come from the outer reaches of the Solar System, where the temperatures are much colder.

由石块，尘土，气体和冰组成的彗星来自于太阳系外部那里温度比较低。

In it, they singled out two foremen, saying they repeatedly failed to clean conveyor belts or apply rock dust used to neutralize explosive coal dust, all leading to unsafe conditions.

在其中，他们挑出了两名工头，称他们多次未能清洁传送带或应用用于中和爆炸性煤尘的岩粉，所有这些都导致不安全的情况。

There are three main parts of a comet: the nucleus, or solid central structure made of rock, dust, and ice; the coma, or dust and gas forming a thin atmosphere around the nucleus; and the tails.

彗核，即由岩石、尘埃和冰构成的中心固体结构，彗发，即由尘埃和气体在彗核周围形成的稀薄气体，还有彗尾。