mammals

例句：

1. 1.Mammals are the only animals that give birth to live young.
   哺乳动物是唯一能产活仔的动物。
2. 2. The study of mammals is important for understanding evolution.
   研究哺乳动物对于理解进化非常重要。
3. 3.Many mammals are herbivores, which means they eat plants for food.
   许多哺乳动物是食草动物，这意味着它们以植物为食。