As a principal verb
As a principal verb do is used in the sense of perform or act.
I did my duty well.
Do as I do.
Can’t you do it yourself?
As an auxiliary verb
The auxiliary do is used in three ways.
To ask a question
The auxiliary do and its forms does and did are used to ask questions in the simple present and simple past tenses.
Read the sentences given below:
I know where John lives. (Affirmative)
Do you know where John lives? (Interrogative)
They take him for a fool. (Affirmative)
Do they take him for a fool? (Interrogative)
To form a negative statement
The auxiliary do and its forms are used to change an affirmative sentence in the simple present and simple past tense into the negative.
I saw him last week. (Affirmative)
I did not see him last week. (Negative)
They want an answer. (Affirmative)
They do not want an answer. (Negative)
He gave me a gift. (Affirmative)
He did not give me a gift. (Negative)
To emphasize an assertion
The auxiliary be is sometimes used to emphasize an assertion.
I do admit that I was wrong. (More emphatic than I admit that I was wrong.)
Do sit down.
They did say that they would help.
He did come.
Fill in the blanks with appropriate forms of be, have and do.
1. I will leave for Mumbai after I —————– finished my work here.
2. She ————— playing the piano when I entered the room.
3. The boy ——————— become unconscious before the doctor came.
4. ——————– you ever been to Darjeeling?
5. That is what he —————- not seem to understand.