help me about promise...

What? Without knowing more about the context of your question, its hard to reply. Do you mean a spoken promise?

Verbal promises are just words. You can't control another persons words or actions.

To some, a promise is an almost unbreakable commitment. To others, it is merely words spoken for a moment of convenience.

There are also legal definitions, but generally only the person making the promise can be held to it, and often not then. They are, as I'm sure Carl will agree, worth about as much as the paper they are written on. ;)