Leaning a language is not a matter of acquiring a set of rules and building up a large vocabulary. The teacher’s effort should not be directed at informing his students about a language, but at enabling them to use it. ——节选自新概念英语教程前言(作者：亚历山大 何其莘)
In order to become a skilled performer, the student must become proficient at using the units of a language. And the unit of language is not, as was once commonly suppose, the word, but the sentence. Learning words irrespective of their function can be a waste of time, for not all words are equal.
Learning words irrespective of their function can be a waste of time, for not al words are equal…Words like I, You, he are structural. Their use can be clearly defined; they are part of a grammatical system. Words like tree, plant, flower are purely lexical items and in no way part of a grammatical system. From the learner’s point of view, skill in handling structural words is the key to mastering a language, for the meaning that is conveyed in sentence-patterns depends largely on the function of the structural words that hold them together.
