not a bit

Từ điển Oxford Advanced Learner 8th

not a ˈbit | not one (little) ˈbit idiom
not at all; not in any way
•‘Are you cold?’ ‘Not a bit.’
•It's not a bit of use (= there's no point in) complaining.
•I don't like that idea one bit.
Main entry: ↑bit_idiom