Understanding has two directions:
One is a negative understanding: putting the subject on the "sunken ship" and "sick tree", watching the new things and future generations pass by and grow up, and lamenting the ruthlessness of the years and the arrival of the old things.
One is a positive understanding: the subject is placed on "Qian Fan" and "10,000 mu", describing that the new forces have surpassed the old things and advanced with unstoppable force.