请求便条
I shall feel obliged if you will favor me with a call at your earliest convenience.（如您方便，请早日来电，我将不胜感激。）
感谢便条
I am writing to tell you how grateful I am for. . .
邀请便条
We should be very glad if you could come. . .
道歉便条
I'm so/terribly/extremly sorry that …
