mastodon/ˈmæs.tə.dɑːn/名词(一万年前即已灭绝的)乳齿象Mammoths, mastodons, sloth, and bison roamed the land.那时猛犸象、乳齿象、树懒和野牛漫步在这片土地上。想跟读,去练习