2022年7月21日
coal
摘要： Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata [stratum(层)的复数] called coal seams [层]. Coal is mostly carbon wit 阅读全文
posted @ 2022-07-21 20:04 华容道专家 阅读(186) 评论(0) 推荐(0)