1. Overview:
The words "do" and "does" are auxiliary verbs. They help form questions and negatives in the present simple tense. "Do" is used with I, you, we, and they. "Does" is used with he, she, and it. They are important for asking questions and making negative sentences.
2. Cases of Usage:
Case 1: Affirmative sentences
In affirmative sentences, we generally do not use "do" or "does" as auxiliary verbs.
Example: She plays soccer.
However, "do" and "does" are used in affirmative sentences when they act as the main verb.
Examples:
I do my homework.
She does the dishes.
Case 2: Negative sentences
To make a negative sentence, use "do not" (don't) with I, you, we, they, and "does not" (doesn't) with he, she, it.
Example: He does not like coffee.
Case 3: Questions
To ask questions, start with "do" or "does."
Example: Do you want to go to the park?
3. Exceptions or Things to Pay Attention To:
There are some exceptions where "do" and "does" are not used. For example, in sentences with modal verbs (can, should, must), we do not use "do" or "does."
Example: She can't swim. (not She doesn't can swim.)
