化石燃料（如煤和石油）属于有限资源。The fossil fuels (coal and oil) are finite resources.发电站烧的煤产自鲁尔地区。The power stations burn coal from the Ruhr region.酸雨并非简单地由烧煤造成。Acid rain is not straightforwardly attributable to the burning of coal....
A white chalk chalks white on a black blackboard.一根白色的粉笔在黑色的黑板上写白字.His steed was by chalks the best.他的马是最好的.The prisoner has walked his chalks , and is off to London.那囚犯逃走了, 逃到伦敦去了....drawing a small picture with coloure...