coal and rock

• 煤岩

coal and rock的用法和样例：

例句

1. Coal rock can be classified as humic and sapropelic coal.
   在煤岩的分类中，有腐殖煤和腐泥煤之分。
2. Linear regression method was used to analyse the effects of maceral and rank on morphology of coal and corresponding char.
   本文用多元回归方法，分析煤岩相组分和煤阶对煤及相对应煤焦表面形态的影响。