1. Mammals feed their young with milk.
哺乳动物用乳汁喂养幼崽。

2. Humans are mammals.
人类是哺乳动物。

3. Many mammals live in forests and grasslands.
许多哺乳动物生活在森林和草原中。

4. Dolphins are intelligent marine mammals.
海豚是聪明的海洋哺乳动物。

A: Are whales mammals or fish?
A：鲸鱼是哺乳动物还是鱼类？

B: Whales are mammals that live in the ocean.
B：鲸鱼是生活在海洋中的哺乳动物。

1) 一类用乳汁喂养幼崽的动物

2) 具有体温恒定特征的脊椎动物

3) 包括人类在内的动物类别

1. 哺乳动物的统称，具有乳腺并哺乳幼崽

e.g. Mammals usually give birth to live young.
哺乳动物通常直接产下幼崽。

noun

1. Warm-blooded vertebrate animals that have hair or fur and produce milk to feed their young.