参考答案：

解析：The relationship between the grammatical forms of a language and their communicative functions is not a one-to-one correspondence. Whereas the sentence structure is stable and straightforward, its communicative function is variable and depends on specific situational and social factors. The fact is that a single linguistic form can express a number of functions, so also can a single communicative function be expressed by a number of linguistic forms. In a communicative perspective, this relationship is explored more carefully, and as a result our views on the properties of language have been expanded and enriched.