西方许多从事二语习得研究的学者认为,二语习得研究必须回答两个核心问题:一是建构什么样的语言理论,二是建构什么样的语言习得理论。前一个问题是后一个问题的基础,后一个问题是前一个问题的延伸和补充。用Lydia White的话来说,“语言习得理论取决于语言理论。若弄不清语言到 Many Western scholars engaged in second language acquisition research believe that second language acquisition research must answer two core questions: First, what kind of language theory is constructed; second, what kind of language acquisition theory is constructed. The former problem is the basis for the latter problem, and the latter problem is the extension and supplement of the previous one. In Lydia White’s words, "the theory of language acquisition depends on the theory of language. If you do not understand the language