i really dont know what i could have done yesterday evening

i really dont know what i could have done yesterday evening I really dont know what to i don't know _ good they could have done.A.howB.that C.what i dont think about what i have done,i think about what i hav I have done what I could do 是对的还是I have done what I could do I really don't know what ----------him yesterday. Thank you.I know what I should have done 到底是 i really dont know 还是 i dont really know 这个副词到底放哪里? i dont know what do you say What I have done 歌词 what I have done 意思 英语翻译原话是这样的：soo..I dont know what to do,I just feel really sa