美国语言学家克拉申(S.D.Krashen)提出了“语言习得理论。他认为成年人发展外语能力主要依靠两个途径:一种是习得(acquisition),另外一种是学习(learning)。所谓“习得是指学习者通过与外界的交际实践,无意识地吸收到该种语言,并在无意识的情况下,流利、正确地使用该语言。而“ SDKrashen, an American linguist, put forward “the theory of language acquisition.” He believes that adults develop their foreign language ability mainly by two means: one is acquisition and the other is learning. “Acquisition refers to the learner’s unconscious absorption into the language through the practice of communication with the outside world, and fluently and correctly using the language unconsciously. and”