一个人的行为,表现.
经常和good连用,be on one's good behavior,意为“（为了给人以好印象）尽量做出良好的表现；（如在试用期或受察看期）规规矩矩,善自检点 ”.
例句：
The minister is coming to dinner,and mother wants us to be on our good behavior.牧师要来吃饭,母亲要我们守规矩.