为什么I am sorry 后要加to do?

为什么I am sorry 后要加to do? I am sorry,sorry ,sorry,I do now want to have this ending.Th i am sorry后动词加to do还是doing I am sorry to see I am sorry to myself I am sorry to do 和I am sorry for doing是同义句还是各自有不同的用法? i am sorry i do not see I am sorry to you I am sorry foryou 翻译：I am sorry to do sth.in ordre to do. Now,i do not know what i should say .In a word,i am sorry to sorry.I just do not know how to say.I feel I am very strange I feel so sorry,I never meart to hurt you .Do you know I am