【正确答案】Dear Zhichao,
[1]Congratulations on your being admitted to the Graduate College of Cornell University! Are you going further studies in the same field as you've been taking up in the undergraduate years?
[2]It has been nearly four years since we met last time at the graduation ceremony. Will you be back during this summer vacation? You know, Facebook could never compare with a face-to-face chat. I still have a vivid recollection of the days when we studied and lived in the same dorm and you were always the best joke-teller.
[3]Looking forward to hearing from you as soon as possible. [4]Congratulations and all best wishes for an even more prosperous future!

【答案解析】这是一封祝贺信。在得知高中最好的室友被国外某大学录取后，向其表示祝贺。信件开头应表明写信的目的；接着阐述对过去的美好回忆以及对室友的惦记；最后再次表示祝贺和祝愿。 [1]开门见山，以Congratulations on sth.结构点明写信的目的。 [2]It has been nearly four years since句型将文章内容过渡到对过去的怀念，使得这一处转折在结构和文意上都很自然。 [3]Looking forward to doing表达出自己对未来的期待。 [4]Congratulations and all best wishes for再次表达了自己的美好祝愿。