tetra-

例句：

1. 1.The quadruped is the first animal to walk on four legs.
   四足动物是第一个用四只腿行走的动物。
2. 2. The tetrapod was discovered in the fossil record.
   四足动物在化石记录中被发现。
3. 3. The tetrapod is a symbol of evolution.
   四足动物是进化的象征。