do for general activity
When we talk about a general activity but do not say what it is, we can use do:
- I want to do something.
- What are you doing this evening?
- What can we do?
- Do it now!
do for work
We usually use do to talk about work:
- What do you do? (= What is your job?)
- Who does your shopping?
- I don't want to do any work today.
- I hate doing the washing up.
- Have you done your homework?
Note that we sometimes use do to replace another more exact verb (but only when the meaning is clear from the situation). This is very informal.
- do the lawn (cut/mow? sow? the lawn)
- do my room (tidy? paint? my room)
- do the car (wash? paint? repair? the car)