知识贝壳
知识贝壳
所属栏目：英汉双解有机化学
A black mineral that consists mainlyof carbon,used as a fuel and as a source oforganic chemicals. It is the fossilized re-mains of plants that grew in the Carbonif- erous and Permian periods and were buriedand subjected to high pressures under-ground. The ......（本文共 376 字 ） [阅读本文] >>