Final answer:
The sentence 'a ball is a toy' demonstrates the ball's class, placing it in a category with other similar objects. In English, understanding form and function helps distinguish how words are used and defined in sentences.
Step-by-step explanation:
The sentence "a ball is a toy" demonstrates the ball's class. This sentence lets us know that the ball is a member of the group or category of things known as toys. Understanding the class of an object helps to categorize it with other items that have similar characteristics or purposes, such as the way "chair" belongs to the category of "furniture" along with "table" and "lamp," because they share the same essence.
In English grammar, the distinction between form and function can be relevant. Form refers to the part of speech of a word as it is defined, while function refers to how the word works in a sentence. The form of a word is static, but its function may change depending on its use within a sentence.