*thank sb sincerely 真诚地感谢某人
* yours sincerely 谨启（用于信件署名前）. =>Usage at your 用法见 your.
if you feel or believe something sincerely, you really feel or believe it and are not just pretending
= truly I sincerely hope I'll see her again. We are sincerely grateful for your help.(yours) sincerely
an expression used to end a formal letter, especially one that you have begun by using someone's name
1. I sincerely hope you will soon recover. 我真诚地盼望你不久就会恢复健康。