0 used with another verb to form questions and negative sentences, including negative orders, and sometimes in affirmative sentences for reasons of style: --
You don't understand the question, do you?
"I want two chocolate bars and an ice cream." "Do you now/indeed? (= that is surprising or unreasonable)."
Little does he know (= he knows nothing about it), but we're flying to Geneva next weekend to celebrate his birthday.
formal So quietly did she speak (= she spoke so quietly) that I could scarcely hear her.
Don't (you) speak to me like that!
"Didn't you realize she was deaf?" "No I didn't."/"Of course I did."
Why did you do that?
Where do you work?
3 to perform, take part in, or achieve something: --
It's a global problem - what can individuals do about it?
She just hasn't known what to do with herself (= how to keep herself busy) since she retired.
US What did you do with (= where did you put) my coat?
UK What have you done with (= where have you put) my coat?
What can I do for you? (= How can I help you?)
What are these toys doing here? (= Why are they here?)
What (on earth) were you doing in the library (= why were you there) at two o'clock in the morning?
US What did you do (= make happen) to her?
UK What have you done (= made happen) to her?
US Why were you sent to the principal's office? What did you do now?
UK Why were you sent to see the headmaster? What have you done now?
What are you doing over the weekend?
That was a really stupid thing to do.
5 connected with: --
"I thought I should tell you I saw your son smoking today." "Mind your own business! What my son does has nothing to do with you!"
She refused to have anything (more) to do with him after he was arrested for drinking and driving.
"But I didn't have any money." "What does that have to do with it? You still shouldn't have taken my wallet without asking me."
"Why did you want to talk to me?" "Well, it's to do with a complaint that's been made about your work."
They're doing fantastically well this season.
The whole nation was force-fed government propaganda about how well the country was doing.
I was doing really well with my diet, but I'm afraid I've let it slide recently.
The fish was done to perfection.