in english, when we need someone's help, we can say starting with : sorry or I am sorry, could you please do me a favor? but in chinese, if you say 对不起,你能帮我一下吗? this is too weird.....you can say : excuse me , can you help me? 打扰一下,你能帮我一下吗?
in english, excuse pardon sorry is the same thing in this case but in chinese.......no.....
if you translate excuse me in chinese word by word, it will become 原谅我, then you think that we can say I am sorry to replace it....in fact excuse me doesn't mean 打扰一下. in other word, we translate this considering the difference of culture.......