Using of course

Of course means ‘without any doubt’ or ‘certainly’.

‘Can you help you?’ ‘Of course.’

‘Can I join your group?’ ‘Yes, of course.’

‘Could you get me something to drink?’ ‘Of course.’

‘Do you know what I mean?’ ‘Of course.’

Of course is also used for giving permission in a polite way.

‘May I come in?’ ‘Of course you may.’

Of course not

Of course not means ‘no’.

Ravi: Could you lend me 10 dollars?

Rohan: Of course not.

Of course not is also used to refuse permission.

Ravi: Can I borrow your car tonight?

Sumesh: Of course not. I need it.