It’s generous of you to take so much interest in my work (to give me so much of your time) (to show me so much consideration).

　　承蒙对我的工作如此操心(为我花费这么多时间)(对我如此关怀)。

　　We are indebted to you…

　　我们感谢你……

　　I regret very much that I did not have an opportunity to thank you personally for …

　　未能面谢，深表遗憾。