porpoise

例句：

1. 1. The porpoise glides gracefully through the water.
   海豹在水中优雅地滑行。
2. 2.The porpoise is a fascinating animal that swims with its flippers up.
   海豹是一种令人着迷的动物，它用鳍游泳。
3. 3. The porpoise is a marine mammal that lives in the oceans and rivers.
   海豹是一种海洋哺乳动物，生活在海洋和河流中。