What is the proof of a person belonging to the class of Mammals?

1) Feeding offspring with milk,
2) the skin is multilayer with various glands, have horn formations – hair,
3) the embryo develops in the uterus,
4) the cerebral hemispheres are covered with cerebral cortex,
5) the presence of the auricles.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.