A, Human Skin (human skin):

Skin: "skin" is the most commonly used word to represent the external covering of human body. For example:

Her skin is smooth. She has smooth skin. )

Skin care is essential for a healthy lifestyle. )

Second, the animal skin (animal skin):

Fur: "Fur" is usually used to describe the skin of animals, especially the hair covering animals, such as:

Foxes have thick fur to keep warm in winter. Foxes have thick fur and keep warm in winter. )

Animal skins (animal skins, leather): "Animal skins" are often used to refer to animal skins made of leather in the sense of animal skins, such as:

This bag is made of cowhide. This bag is made of cowhide. )

Third, the plant epidermis:

Peel: "peel" is usually used to describe the skin of a fruit or vegetable, for example:

She peeled oranges and ate them. She peeled the orange and began to eat. )

Fourth, the shell of the object:

Peel (hard skin of fruit): "peel" is used to refer to the hard skin of fruit, usually referring to the peel of citrus fruits, such as:

He ate the orange, leaving only the peel. He ate the orange, leaving only the peel. )

Bark: "Bark" is the outer covering of trees, such as:

The bark of this tree feels rough. )

The above is about the English expressions of "Pi" in different contexts. These words are used to describe all kinds of skin, covering or skin in daily life, and the specific choice depends on the object and context described. Clever use of these words can enrich your English expression.