本文章由春喜在線英語于2017.2.24日編輯發布 

    古人云，“少壯不努力，老大背單詞”。各位掙扎在紅黃藍黑各種寶書中的同學或許要問，這單詞要背到什么時候才算夠？我們不妨來看看外國人的詞匯量是多少。

　Britain’s Guardian newspaper, in 1986, estimated the size of the average person’s vocabulary as developing from roughly 300 words at two years old, through 5,000 words at five years old, to some 12,000 words at the age of 12. 

1986年，英國《衛報》估算英國人2歲的單詞量約為300個，5歲時為5000個，到了12歲，詞匯量在12000個左右。

The Guardian’s research suggested that it stays at around this number of words for the remainder of most people’s lives—adding that this is roughly the same number of words as those drawn on by a popular newspaper in the course of producing its daily editions—while a graduate might have a vocabulary nearly twice as large (23,000 words). Shakespeare had one of the largest recorded vocabularies of any English writer at around 30,000 words. 

　　《衛報》的研究認為大多數人之后的詞匯量都不會有太大的變化。它還指出，12000詞匯量基本等同于流行報紙每天文章里的詞匯量。但是大學畢業生的詞匯量大約是其2倍，約23000個。莎士比亞則是所有英語作家中詞匯量最大的之一，高達約30000個單詞。 

Francis and Kucera (1982) suggest that the 2000 most frequent word families of English make up 79.7% of the individual words in any English text, the 3000 most frequent word families represent 84%， the 4000 most frequent word families make up about 86.7%， and the 5000 most frequent word families cover 88.6%. 

　　Francis和Kucera在1982年發表的研究結果稱，2000個最常用單詞覆蓋了79.7%的英文文本內容，最常用的3000單詞及變形的覆蓋率達到84%，4000最常用單詞及變形的覆蓋率為86.7%，當詞匯量增加到5000時，覆蓋率為88.6%。 

　　綜上所述，英語學習者的第一個目標是2000常用單詞，這樣就能看懂將近80%的英文內容。至于終極目標則是20000單詞，也就是和受過良好教育的英國人的詞匯量相當。 

　　需要注意的是，認識單詞和會用單詞是兩碼事。詞匯量達到一定水平后，在對話、寫作中使用這些單詞的能力對英語水平的影響更大。