Consideration is an important term in english and american contract law , and it is a body of rules enriched by the development of common law . there are many rules about consideration , among which the following may be most frequently mentioned : past consideration is no consideration ; consideration is provided by the promisee , though not necessarily to the promisor ; the adequacy and sufficiency of consideration 对价是英美合同法中的一个重要术语，有关对价的制度是随着普通法的历史发展而不断丰富起来的规则体系，有关对价的规则主要有：既往对价不是对价；对价一般由受约人提供，但不一定提供给立约人；对价的充足与充分。
