14. Learning a language 学习一种语言

A: To speak a language, one must know its grammar almost completely, not just its vocabulary or its sounds, not even sets of rules for constructing sentences. But one can't learn a language by studying only its grammar. If you do this, you may learn only the grammar and not the language. Instead, by memorizing how to use them, one can learn both the grammar of the language and the language.

A great many-a great deal