1·He's the kindest and sincerest person I've ever met.
他是我见过的最和善、最真诚的人。
—— 《柯林斯英汉双解大词典》
2·Once again, I beg you accept sincerest apologies for the unfortunate carelessness, and I await anxiously your next move.
因为我不幸粗心大意,再次恳求你接受我最真诚的道歉,我急切地等待你的下一步。
3·Please accept my sincerest and deepest apology for…
请接受我最真诚的致歉……