For once, she lost/dropped her customary reserve and became quite lively.
这次,她一反平素的沉默寡言,表现得很活跃。
It's customary to give people gifts on their birthdays.
给人送生日礼物是惯常的事。
customary详细解释
cus.tom.ar.y adj.(形容词)Commonly practiced, used, or encountered; usual.See Synonyms at usual 习惯上的:共同实施、使用或遇到的;通常的参见 usualBased on custom or tradition rather than written law or contract.按惯例的:基于习俗或传统而不是成文法或合同的 【引伸】 cus.tomar.ily cus.tomar.iness n.(名词)