sincerely的形容词名词是？

She is never completely sincere in what she says about people.

她谈论别人，一向不尽坦诚。

She was sincere and genuine in her wish to make amends for the past.

她诚恳而真心地希望弥补过去的.错误。

I am writing to express my sincere gratitude for your help in my study.

我写这封信是为了感谢你在学习上对我的帮助。