The usage of the auxiliary verb “do” and its forms “does” and “did” is known as do-insertion or do-support.
Uses of Do-Insertion:
The addition of do would turn an assertive sentence in a question. For instance, consider the sentence:
You need to eat lunch.
Adding “do” makes it an interrogative sentence.
Do you need to eat lunch?
Furthermore, the forms of do such as “does” and “Did” are used for the same thing.
- You eat your lunch.
- Did you eat your lunch?
- He likes music.
- Does he like music?
Making negative sentences:
The addition of “not” along with the auxiliary verb makes it a negation.
- You need to rush to school.
- You do not need to rush to school.
- He listens to music.
- He does not listen to music.
- He likes music.
- He does not like music.
For “Be” verbs and “Have” verbs we do not have to add auxiliary verbs to either make it interrogative or to create a negative sentence.
BE & HAVE:
- You are an amazing painter.
- You are not an amazing painter.
But we can’t say:
You do not an amazing painter.
Similarly, to make it an interrogative sentence.
Are you an amazing painter?
Do you an amazing painter?
We can say: “Have you slept well?”
Not: “Do you slept well?”
For imperative sentences:
When using “do” with an auxiliary verb it puts extra emphasis on an imperative sentence.
- “Bring that”
- “Do Bring that!”
In a Tag question:
To make a simple sentence into a tag question we add “not” along with “do”. Consider the following examples:
- We need to order something, don’t we?
- He plays guitar well, doesn’t he?
Giving answers in “Yes/No”:
In order to answer short questions where we say a “Yes” for positive and “No” for a negative response, we add “do”.
Q) You like mangoes?
ANS) Yes I do.
Q) You work here?
ANS) No, I don’t.
However, the rule does not apply to “be” verbs:
Q) Have I been rude?
ANS) No haven’t.
Q) Are you tired?
ANS) Yes, I am.
“Do” can be used for third-person interrogative questions.
- He plays well.
- Does he play well?
At times, the use of the past tense of “do” has to be used which changes the tense.
- He played well.
- Did he play well? (question)
- He did not play well (Negation)
Modal verbs also act like the auxiliary verbs, similar to “Do” they can be inserted to make a tag question, interrogative sentences, and negative sentences.