还有，信用卡公司须在欠款到期前，至少提前二十一天递出结算单。

Also, companies will have to send out billing statements at least twenty-one days before a payment is owed.

youdao

记得六年前，在六月份，我们曾经搞了一个二十一天的隐居静修。在讨论了《华严经》后，曾有一次非常美妙的漫步。

I remember six years ago we had a June retreat for 21 days, and after the talk on the Avatamsaka, there was a very beautiful walk.

youdao