中介语语法是既非L1语法亦非L2语法的自然语法,语法知识并不总是有形态表现,形态运用不能作为二语习得的充分必要证据。形式和形态不是同一个概念,形式是抽象的、看不见的,形态则是具体实现,二者未必有一一对应关系。显性形态的习得与抽象句法知识的习得可能是分离的,并非同步,句法和形态的映射才是二语习得的关键;中介语语言能力取决于学习者的句法一形态映射。 Interlanguage grammar is neither natural grammar nor L2 grammatical grammar of grammar, grammatical knowledge does not always have the form of performance, morphology can not be used as sufficient necessary evidence for second language acquisition. Form and form are not the same concept, form is abstract, invisible, form is the concrete realization, the two may not have one to one correspondence. The acquisition of explicit morphology and the acquisition of abstract syntactic knowledge may be separated, not synchronization, syntax and morphological mapping is the key to second language acquisition; interlanguage language ability depends on the learner’s syntactic and morphological mapping.