As the saying goes: before the flood, build a dike, and the jackal will sharpen the knife first in the future. Isn't this story telling the truth? Be prepared for a rainy day and be prepared for danger in times of peace. Only in this way, when the danger suddenly comes, we won't be in a hurry. In fact, the same is true of learning. "You hate less when you use books." Usually, if you don't enrich your knowledge, it's too late to cram.