What are the differences between "sorry to keep you waiting" and "sorry for keeping you waiting"?
It seems that a lot of native speakers do not distinguish "sorry to do" and "sorry for doing".
But this site says:
To be sorry to + infinitive = to apologise for a present action
I´m sorry to interrupt but could you come with me for a second?
To be sorry for + verb with -ing = to apologise for a past/earlier action
I´m sorry for lying to you, I won´t do it again
"sorry to keep you waiting."==> I will let you wait after I say this
"sorry for keeping you waiting."==> I let you wait before I say this.