写作思路：从文章的写作目的、中心主旨入手，以使文章中心思想鲜明、深刻地表现出来，正文：
Dear Robin,
I am writing to express my gratitude for your invaluable assistance in mastering English, both written and spoken.
Throughout the duration of your class, I have gained immense knowledge from your teachings, which have been instrumental in my language journey. Firstly, you have enlightened me about the Western thought pattern— characterized by directness. This understanding is invaluable, particularly in the context of my academic assessments and interactions with individuals from diverse cultural backgrounds.
Furthermore, your class has significantly bolstered my confidence in English communication. It took me considerable time to cultivate this self-assurance, but now I am more than ready to voice my thoughts in English whenever possible. This newfound confidence is a game-changer.
Lastly, I have discovered a newfound passion for English studies. What was once a mere requirement to pass exams has transformed into an engaging and enjoyable pursuit. Whether it's reading, listening, or speaking, these activities are now brimming with interest, and I thoroughly relish every moment.
Once again, I extend my heartfelt thanks to you, Robin. Your dedication and time are greatly appreciated.
Warm regards,
[Your Name]
