as an orderly system of rules which a learner can consciously acquire by study methods.Both the generative transformational and cognitive theories have recognized a language as an orderly system of rules which a learner can consciously acquire by study methods. 生成转换理论和认知理论都承认语言是一种有序的规则系统，学习者可以通过学习方法有意识地获得规则。
