This is a red-letter day for you.
今天是你的大好日子。
a red-letter day直译过来就是：“有红色字母的一天”，这个短语的正确意思是：“值得纪念的或喜庆的日子”。因此，当美国人说"This is a red-letter day for you."时，他/她要表达的意思就是"Today is very important for you."、"It's a special day for you."。
情景对白：
Shirley: I'm so excited that I'm raised to management at today's conference.
雪莉：我太高兴了，今天的会议上我被提拔到管理层了！
Jane: Wow, this is a red-letter day for you. Congratulations!
简：哇，今天是你的大好日子。祝贺你！
搭配句积累：
①The boss praised me for my outstanding performance.
我表现出色，受到了老板的表扬。
②I got promoted today for hard working.
由于工作努力，我今天升职了。
③My idea is approved by the board of directors.
我的创意竟被董事会采纳了。
④Today I will sign a contract with the government on behalf of the company.
今天我将代表公司跟政府签一份合同。
单词：
1. red-letter adj. 值得纪念的
People are well dressed on red-letter day.
在喜庆的日子里，人们身著盛装。
This has been become internationally one celebrates a red-letter day.
这已经成为国际性的一个庆祝节日了。
This is a red-letter occasion.
这是一件值得纪念的事。
2. board of directors 董事会
The Board of Directors has approved the decision unanimously.
董事会成员一致批准了该项决定。
The board of directors canvassed his design thoroughly.
董事会彻底讨论了他的设计。
He's trying to curry favor with the board of directors.
他想要巴结董事会。
3. on behalf of 代表
The agent spoke on behalf of his principal.
代理人代表他的委托人说话。
Governor appointed by the queen on behalf of the exercise of authority.
由女王任命的总督代为行使职权。
You said you would have one more beer on behalf of your brother that day.
你说你那天替你的哥哥多喝一杯。
