n.青石；硫酸銅
The bluestone he is standing on is the material for covering this road. 他腳下有一塊青石板，這條路都是用這種石頭鋪成的。
Standing on bluestone door steps, she was so excited that her heart felt shaking. 她站在青石臺階上，心里激動得發(fā)抖。
