first category

• 第一纲

first category的用法和样例：

例句

1. Either of the first pair of fanglike appendages near the mouth of an arachnid,such as a spider,often modified for grasping and piercing.
   螯肢蜘蛛等蛛形纲动物在嘴边的第一对肢状附属物，常用来抓握和刺穿物体。