What is the significance of the so-called "foreshadowing" in some words in A Dream of Red Mansions?

The foreshadowing is the foreshadowing of the last article. There are many foreshadowing in A Dream of Red Mansions. When Zhi Yanzhai said that A Dream of Red Mansions was "a thousand miles of grass and snake gray lines", he meant a lot of foreshadowing and it was very important. The most important thing is the fifth chapter. Twelve poems and twelve songs are the important inspirations of many women in A Dream of Red Mansions, and are the important basis for the lost scientists to study the dream of Red Mansions after 1980s. According to the content of Chapter 5, the Redologists have got the general results about the twelve women in Jinling.