在撰写英语祝贺信以祝贺他人考研成功时，你可以遵循以下结构和要点：
开头问候：
使用`Dear [姓名],`来开头，表达你的敬意和祝贺。
表达祝贺：
在信的开头直接表达你对对方考研成功的祝贺和高兴之情。
肯定成就：
提及对方的努力和成就，如提到对方的学习能力、坚持和才智。
表达祝福：
使用温馨的话语祝愿对方未来的学术和职业生涯顺利。
结束语：
用`Sincerely/Best wishes/Best regards`等表达你的良好祝愿。
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Dear [姓名],
I am writing to express my heartfelt congratulations on your recent success in the postgraduate entrance examination. Your dedication and hard work have paid off, and I have no doubt that you will excel in your future academic pursuits.
Your dedication and commitment to your studies have always been an inspiration to those around you. I am confident that you will make a great contribution to your field of study. May your journey in graduate school be filled with joy, discovery, and success.
Please accept my best wishes for your future endeavors. I look forward to hearing about your progress.
Sincerely,
[你的名字]
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记得根据具体情况调整信中的内容和语气，确保信件既真诚又具有个人色彩。祝你考研顺利!