pick up on something

Từ điển Oxford Advanced Learner 8th

ˌpick ˈup on sth derived
1. to notice sth and perhaps react to it
•She failed to pick up on the humour in his remark.
2. to return to a point that has already been mentioned or discussed
•If I could just pick up on a question you raised earlier.
Main entry: ↑pick_derived