behaving right行为规矩 While his father was around，the boy was on his good behavior， but when the father left， the boy soon got into mischief．父亲在场时，这孩子规规矩矩，但父亲一走，他马上就调皮起来。 The naughty boy is on his best behavior today．今天这个调皮鬼表现很好。
on one's best ／good behavior
behaving right行为规矩 While his ancestor was around，the boy was on his acceptable behavior， but back the ancestor left， the boy anon got into mischief．父亲在场时，这孩子规规矩矩，但父亲一走，他马上就调皮起来。 The annoying boy is on his best behavior today．今天这个调皮鬼表现很好。 Dictionary
An on one's best ／good behavior idiom dictionary is a great resource for writers, students, and anyone looking to expand their vocabulary. It contains a list of words with similar meanings with on one's best ／good behavior, allowing users to choose the best word for their specific context.
類似の言葉の辞書、別の表現、同義語、イディオム イディオム on one's best ／good behavior