对于二语学习者来说,词汇是二语习得中最重要的语言变量,学习者掌握的词汇越多,支配语言的能力就越强。不管学生的语法学得有多好,不管学生二语词汇的发音掌握得有多好,如果没有单词来表达广泛的意义,那么二语的交际不可能是有意义的。(McCarthy 1990:viii) For second-language learners, vocabulary is the most important linguistic variable in second language acquisition. The more vocabulary learners possess, the greater the ability to control the language. No matter how good the student’s grammar is, regardless of how well the student’s second language vocabulary can be pronounced, if there is no word to express a wide range of meanings, then the second language communication cannot be meaningful. (McCarthy 1990:viii)