【正确答案】
[范文]
Dear Ms. White,
Thanks for your letter about the heating system. We have had a plumber check the system today and we were told that the system was too old and that it had to be replaced. The contractor will send workers to install a new furnace the day after tomorrow. So for today and tomorrow there , will be no heat for the entire building, but please rest assured that the new heating system will work before the cold front arrives this weekend.
We apologize for the Inconvenience. And we value your understanding and cooperation.
Li Ming
Building Supervisor

【答案解析】[审题]
便笺也叫做便条，是一种简便的信函，形式简单，主要用于询问、道歉、请假、约会、留言等事由。与一般书信相比，便笺可以省略以下几项：收信人和发信人的地址；日期中的年份。