cordial; devout; heartfelt; wholehearted

1. 她向他表示衷心的感謝。
   She gave him her heartfelt thanks.
2. 我謹向各位表示衷心的感謝。
   My heartfelt thanks to you all.
3. 他們向我們表達了他們衷心的感激。
   They expressed their heartfelt gratefulness to us.
4. 親愛的老師，向您表達我最衷心的感謝。在人生旅途上，您為我點燃了希望之光，您所做的一切潤澤了我的心靈，開闊了我的視野。今天我向您致以崇高的敬意。
   My heartfelt thanks to you, dear teacher. On the voyage of life, you have kindled the light of hope for me. What you have done enriches my mind and broadens my view. On this day I honour you sincerely.

心的英語翻譯：