How to differentiate for and to?

how to differentiate for and to?
when we should use for or to?

Hi,

One example and this is only one example: I have answered this question for you - I have sent a message to you.

Alan

thanks
how about this sentence

i bought a present to her
or
i bought a present for her

Hi YL

Only “for” works in your sentence:

  • I bought a present for her.
    .

thanks
but can you explain when we should use for and when we should use to?
for should follow by what?
and
to should follow by what?[/b]

Hi My Man. You should post your difficulties about the use of “to” and “for” in order to be helped,because we don’t know exactly your difficulties…For example, write: “I do this work to you” and the correct sentence is I do this work for you. that is to say: I work at your place. trésorUnikin

You should aslo go to the url: www.esl.about.com/library/grammar/blgr_prep4.htm

TréosUnikin