The auxiliary verb do is used in a lot of ways.

We use do to make questions with ordinary verbs, but not with auxiliary verbs. Compare:
Do you like I Can you /

We use do to make negative sentences with ordinary verbs, but not with auxiliary verbs. Compare:
I don't like football.
I can't play football.

We use do instead of repeating a complete verb or clause.
She doesn't like dancing, but I do (= ... but I like dancing.)
Ann thinks there's something wrong with Bill, and so do I.
You play bridge, don't you?

We use do in an affirmative clause for emphasis.
Do sit down. She thinks I don't iove her. but I do love her.

We can use the auxiliary verb do together with the ordinary verb do — so that we have do twice in the same verb phrase.
What do you do in the evenings?
'My name is Robinson.' 'How do you do?

Tips to succeed in Exams

Organise your time

The most helpful strategy Dan could adopt is to set time limits. In the short term, this would give him an idea of when his work would finish. As it is, he simply gives himself all evening. This is very inefficient. Time limits would also help him complete his long term tasks in good time. Left to his own devices, he wastes precious weeks his procrastination is understandable, given that he finds working so difficult . A timetable would be a good start.