In terms of English onomatopoeic words, which of the following statements can be regarded as the truth（）
A. They can be used as verbs, adjectives, adverbs and nouns.
B. In fact they are used most frequently as nouns and verbs, the two most forceful word classes.
C. Onomatopoeic words are small in number in English but they are very active.
D. The grammatical functions they can serve include the subject, the predicate, the object, the attribute and the adverbial.
