About content words and functional words, which of the following statements is NOT true?（ ）
A.Content words include nouns, verbs, adjectives, adverbs and numerals. B.Functional words don't have notions of their own. That's why they are called empty words. C.Functional words do far more work of expression in English than content words. D.The chief function of content words is to express the relation between notions.正确答案D
