【正确答案】正确答案：Stemming from Firth's theories in the London School, Halliday's Systemic-Functional (SF) Grammar is a socially oriented functional linguistic approach and one of the most influential linguistic theories in the 20th century, exerting a strong impact on various disciplines related to language, such as language teaching, sociolinguistics, discourse analysis, stylistics, and machine translation. It actually has two components; Systemic Grammar and Functional Grammar. They are two inseparable parts for an integral framework in Halliday's linguistic inquiry. Systemic Grammar aims to explain the internal relations in language as a system network, or meaning potential. And this network consists of subsystems from which language users make choices. Functional Grammar aims to reveal that language is a means of social interaction, based on the assumption that language system and the forms that make it up are inescapably determined by the users or functions which they serve.