【正确答案】正确答案：According to Halliday, structure is the outward form of the system, which lies behind the former. Structure, therefore, is less abstract, and closer to the "surface". By studying the constituency structure of grammar, it is assumed that the semantic system above it could become plausible. In the constituency structure, elements are recognized with reference to their functions in relation to the whole. Therefore, in "The huge tiger climbed a tree", only elements like "the huge tiger" not "the" or "the huge" could be recognized, since it is the whole sequence that plays a role in the clause, and in this sentence, the role is Subject. This is the way of bracketing used in Systemic-Functional Grammar. This step is followed by labeling, which is to reveal the specific function of that element in relation to the whole. For example, by labeling "the huge tiger" a functional label; "Subject", we get to know the interpersonal function that element plays. It is through these two steps the structures are related to the functions performed by language.