"Hmmmmm, what u mean??"

What I mean is this:

The description of your problem shows a considerably higher level of 8051 knowledge than the question you have asked. This is normal when students who do not wish to do the work themselves post a homework assignment.

If you understand how timers work, which you appear to from the problem description, you should have no difficulty working out how to generate your three duty cycles.

" I have think this few day liau, but still cant solve it :("

If you have, then you must have made some attempt to get it working. Why don't you post the code to show some intent, then maybe you'll receive some help?