誠心誠意

Simplified: 诚心诚意

On the HSK 7-9 vocabulary list, at CEFR level C2.

chéngxīnchéng ㄔㄥˊ ㄒㄧㄣ ㄔㄥˊ ㄧˋ

    • earnestly and sincerely (idiom) with all sincerity

Character by character

Sources