Reason:

1, prefix: opening point; Render the atmosphere (prose), pave the way (narrative), and set suspense (novel, but not tested in Shanghai) as the auxiliary paving way for the following; Below the general collar;

2. In the text: connecting the preceding with the following; Below the general collar; Summarize the above;

3. At the end of the article: point out the center (prose); Deepen the theme (narrative); The beginning of a quotation (argumentative, narrative, novel)