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。

His gruff exterior concealed one of the kindest hearts.

他不友好的外表下藏着一颗最善良的心。

The kindest animal is you, Mother Kangaroo. Even when you were worried about your Joey, you were still kind to a grumpy complaining old wombat.

最善良的动物就是你，袋鼠妈妈。即使你在很担心你的乔伊的情况下，还是对一只爱发牢骚的坏脾气老袋熊这么好。