unsealed letter
常见例句
- This is an unsealed letter, don't read it.
信函送到时是开着口的。 - They became even more popular in Britain when a card could be posted in an unsealed envelope for one half-penny - half the price of an ordinary letter.
当邮寄非密封的卡片只要半便士（普通信件邮费的一半）时，邮寄贺卡变得异常流行。 返回 unsealed letter