在派对上,主人迎接所有客人是惯例。
It is ___customary for the host to greet all the guests at the party.
青少年之间见面时交换社交媒体账号是常见的。
Among teenagers, it is ___customary to exchange social media handles when they meet.
在许多社会,受邀去别人家时带礼物是习俗。
In many societies, it is ___customary to bring a gift when invited to someone's home.