The back wave of the Yangtze River pushes the front wave, and the front wave dies on the beach. This sentence comes from an ancient poem by China. Its original intention is to describe that things are constantly developing and new things are constantly replacing old things. Here, "the waves behind the Yangtze River push the waves before" vividly shows the process of this substitution and development, which means that new forces are constantly rising to replace the old forces.