【正确答案】As to the question about how to understand different sentence structures, there are two important language theories, one is the transformational-generative grammar proposed by Noam Chomsky, and the other is the systemic-functional grammar proposed by Halliday.
Accordingly, Chomsky suggests us to make a distinction between two levels of structures: deep and surface structures. And the aim of linguistics is to produce a generative grammar.
As the name suggests, systemic-functional grammar has two characteristics: systematic and functional. It explains the internal relations in language as a systernic network, or meaning potential. It views language as a form of doing rather than a form of knowing, and it distinguishes linguistic potential from actual language behavior.
Halliday's theory paid more attention to paradigmatic relations than to syntagmatic relations which is the main concern of Chomsky.

【答案解析】[解析] 本题考查乔姆斯基和韩礼德的不同理论。乔姆斯基提出转换生成语法。转换生成语法是将句法根据深层结构和表层结构来进行描述。韩礼德提出的系统功能语法可以分成“系统语法”和“功能语法”两个部分。他认为语言的性质决定人们对语言的要求，即它所必须完成的功能。同时，韩礼德在研究语言时，更关注语言的聚合父系，这一点是他的理论与乔姆斯基的思想最大的不同所在。