The verb to do can be used as an auxiliary and a main verb. It is often used in questions.
I / you / we / they
Perfect: have / had done
Continuous: am / are / were doing
he / she / it
Perfect: has / had done
Continuous: is / was doing
In Present Simple third person (he, she, it), add an ‘es’ to a verb that ends in ‘o’: do > does / go> goes
As an action verb:
John always does his homework on time. Street sweepers do a lot of work around the city. Paul did a great job on his science report for school. You have done nothing all day! I am doing the best I can! Your customer doesn’t understand the contract. You don’t need to worry about me. Your friends didn’t get the email.
Do you want to go to the concert? Does your cat live outside or in the house? Does your sister always talk so much on the phone? Did you catch the train this morning? Don’t you ever visit your relatives? Didn’t Mr. Jones call you? Where do you want to send the letter? Why does she always shout like that? How much do these apples cost? Why don’t you ever tidy up your room? When did they arrive at school?