【正确答案】正确答案：The factor to distinguish connected texts which make sense from those which do not is usually described as coherence. Coherence is traditionally described as the relationships that link the ideas in a text to create meaning for the readers, apart from cohesive devices. It should be noticed that cohesion by itself would not be sufficient to enable us to make sense of what read or hear; it is quite easy to create a highly cohesive text which has a lot of connections between the sentences, but which remains difficult to interpret. And coherence, as the invisible net of a text, performs a function of "connectedness" which makes the text interpretable to people. Regarding the importance of coherence to a whole text, it seems necessary for a teacher of SFL to help students develop coherence in writing. Research has found that in their writing, ESL/EFL students focus almost exclusively on the word and sentence levels rather than the level of the whole discourse, that is, textual coherence. A pedagogical focus on coherence can shift students" attention from sentence-level grammar to discourse features such as textual structuring and propositional unity, which are crucial to creating meaning in texts. Indeed, helping students improve the coherence of their writing ought to be a significant aspect of L2 writing instruction. To help students focus on coherence in writing, it is essential that teachers have a thorough understanding of what makes a text coherent. As is shown in the composition text books, it seems common to regard coherence simply as connectedness between sentences, use of explicit cohesive devices at the paragraph level, and use of connective devices such as pronouns, repetitive structures, and transitional markers. However, coherence should not be narrowed in terms of sentence-level connectedness and paragraph unity rather than discourse unity. Thus, to help students create coherence in their writing, it is necessary for teachers to pay more attention in the broader sense of coherence.