1.2  Vocabulary

      All the words in a language make up what is generally known as its vocabulary. The term 'vocabulary' is used in different senses. Not only can it refer to the total number of the words in a language, but it can stand for all the words used in a particular historical period, e.g. Old English vocabulary, Middle English vocabulary and Modern English vocabulary. We also use it to refer to all the words of a given dialect, a given book, a given discipline(学科领域) and the words possessed by an individual person. English is one of the world's highly developed(高度发展的；高度成熟的) languages. Naturally the vocabulary is one of the largest and richest. The general estimate of the vocabulary is over one million words.