The teacher dwelt _____________ the need of discipline.
The teacher dwelt _____________ the need of discipline.
Explanation
Dwell on is a phrase.
Dwell on means emphasize on something or highlight something.
Dwell on means کسی بات پر زور دینا
He dwelt on the need of discipline انہوں نے نظم و ظبط کی ضرورت پر زور دیا