封信的用法和樣例：
例句
-
這封信需要立即答覆嗎？
Does the letter demand an immediate answer? ie Must it be answered at once? -
這封信有國王的封印。
The letter bears the seal of the king. -
那封信是催促還債的通知，讓我很不痛快。
The letter was an uncomfortable reminder of my debts. -
這是一封信，說(shuō)得更正確些，是一封邀請信。
This is a letter, or more correctly, an invitation letter. -
不可能在五分鐘內打完這封信。
There is no typing up this letter within five minutes.
