Thank you very much for your reply. I am sorry I didn't post my question clearly. What I meant was what is the difference between " as for sb./sth" and " as to sb./sth." Could you please kindly explain the difference to me?
Thank you very much for your explanation. To make sure that I understand your explanation I'd like to show how I understand it:
According to your explanation, both are prepositonal phrase and there isn't any difference between the meanings of them. Is that right?
They both mean pretty much the same thing but I would try to avoid "as to" as it sounds somewhat pretentious and stiff if placed at the beginning of a sentence. "As for" is less formal and sounds much better, I think.