1.mule=donkey+horse 骡子为驴跟马的杂交产物
2.The mule can't breed.骡子MS不能生育.
填空 顺序依次 organism features environment variation facotrs
圈字 environmental variation:having an earring,a scar wearing blue clothes,having a broken leg.
environmental factors:a strong wind,a rainy day,sunshine,a fire