What do you mean by the seven methods of the Long March, the Jinsha River is warm in the clouds and cliffs, and the Dadu Bridge is cold?

"The Jinsha River is warm in the clouds and cliffs, and the Dadu Bridge is cold in the iron rope." On the cliffs on both sides of the Jinsha River, the rushing water beats against the towering cliffs on both sides, giving people a warm feeling; There are only a dozen iron cables left on the Dadu Bridge across the east and west banks, which makes people feel deep chill.

"Clouds and cliffs are warm": the Jinsha River is lapping on the shore, which means the author's optimistic mood. The Jinsha River water slaps on the cliff, which makes people feel very warm (the Red Army is very happy after skillfully crossing the Jinsha River, so it is very warm); There are many iron cables hanging on the Luding Bridge across the Dadu River, which makes people feel chilling (it is very difficult to cross the Luding Bridge in the face of bullets, and I feel very scared, which highlights the courage and tenacity of the Red Army soldiers and expresses the author's praise for the Red Army soldiers). These two poems are selected from the Seven Laws Long March written by President Mao Zedong.

I hope to learn by going up a flight of stairs.