sincere的副词形式为

sincere的副词形式为sincerely、
sincerely：adv、真诚地;诚实地。

I sincerely believe that this is the right decision、

我由衷地认为这个决定是正确的。

'I sincerely hope we shall meet again', he said

“我真心希望我们能再次重逢，”他说。

Maybe he sincerely wanted to help his country

或许他是诚心诚意地想帮助自己的祖国。

He sincerely believed he was acting in both women's best interests、

他真的、认为他的所作所为对两个女人都非常有利。

Are we starting that again? I most sincerely hope not、

我们又要旧事重提了吗？我真的希望不要。