take somebody up on something

Từ điển Oxford Advanced Learner 8th

ˌtake sb ˈup on sth derived
1. to question sb about sth, because you do not agree with them
•I must take you up on that point.
•I'd like to take you up on what you said earlier.
2. (informal)to accept an offer, a bet, etc. from sb
•Thanks for the invitation— we'll take you up on it some time.
Main entry: ↑take_derived