-- Was his father very strict with him when he was at school?
--- Yes. He will never praise him _____ he becomes one of the top students in his grade.
A. after B. unless C. until D. when
-- Was his father very strict with him when he was at school?
--- Yes. He will never praise him _____ he becomes one of the top students in his grade.
A. after B. unless C. until D. when
B