i am really appreciated.
thank you.
thanks a lot.
i am very grateful.
道歉:i am sorry.
sorry.
it's my fault.
I apologize.
I feel sorry about that.
my bad.(口语,very informal)
my mistake.
人家道歉后的回答:
it's ok.
that's all right
that's not your fault.
dont feel sorry.
don't worry about it.
that's nothing.
never mind.
don't feel bad