单数形式

This is a book.

She is a teacher.

They are playing football.

复数形式

These are books.

They are teachers.

We are playing basketball.

不规则变化

Children are fun.

Women are beautiful.

Mice are small.

以o结尾的名词

Tomatoes are delicious.

Potatoes are healthy.

-Heroes are admired.

以辅音字母加y结尾的名词

Babies are cute.

Countrymen are friendly.

以f或fe结尾的名词

Wives are loving.

Knives are sharp.

复合名词

A man's suit is expensive.

A woman's dress is pretty.

不可数名词

Water is essential.

Air is important.

这些例句展示了可数名词在单数和复数形式下的用法，并包括了一些不规则变化的例子。希望这些信息对你有所帮助。