n.磨頂槽
A flat-bottomed, roughly circular volcanic crater of explosive origin that is often filled with water. 小火山口一種底部平坦、大致呈圓形的火山爆發(fā)后形成的盛滿水的低洼地
A rim, as of a vessel, bell, or crater. 邊容器、鈴和坑的邊緣
