词汇学-1.5.2

1.5.2 Content Words and Functional Words
　　By notion, words can be grouped into content words and functional words. Content words denote clear notions and thus are known as notional words. They include nouns, verbs, adjectives, adverbs and numerals, which denote objects, phenomena, action, quality, state, degree, quantity, etc. Earth, cloud, run, walk, bright, dark, never, frequently, five, December are all content words.
　Functional words do not have notions of their own. Therefore, they are also called empty words. As their chief function is to express the relation between notions, the relation between words as well as between sentences, they are known as form words. Prepositions, conjunctions, auxiliaries and articles belong to this category.Examples are on, of, upon, and, but, do (does, did ), be (am, are, were, is), a, the and others.
　 Content words, which constitute the main body of the English vocabulary, are numerous, and the number is ever growing whereas functional words, which make up a very small number of the vocabulary, remain stable. However, functional words do far more work of expression in English on average than content words. According to Stuart Robertson, et al (1957), the nine functional words, namely, and, be, have, it, of, the, to, will, you assume one fourth of the task of expression in English. This is justified by the following examples. Of the total of twenty-seven words, only nine are content words and all the rest are functional words.
[1] It is fun to play with children.
[2] It is certain that they have forgotten the address.
[3] The more I see the film, the more I like it.