Liu Kai bought an agricultural four-wheeler to give floor slabs to others. On this day, when he drove through a simple bridge built with floor slabs, the floor slabs that were built into the bridge may have taken too long, or Liu Kai’s car was too heavy and broke. When the bridge was broken, Liu Kai was not ambiguous: anyway, what he had installed on his car was the floor slab, so just remove one and replace it. Just do it. Liu Kai’s hands and feet were swift, and within a few minutes, he removed the damaged floor and replaced it with a new floor slab pulled up by his car.
 After all this, Liu Kai let out a sigh of relief. He wiped his sweat with his hand and was about to leave. Suddenly on a whim, he ran to the new floor and bounced, and said to the onlookers:
  “The quality of the original floor slab is too poor,-look at the floor slab I pulled is strong and beautiful ——“
  As he said, he jumped again. The danger happened at this moment. With a “bang”, the floor slab broke in the middle. The two ends of the floor quickly moved closer to the middle, sandwiching Liu Kai.
 It turned out that he installed the floor slab upside down because of hectic.
 It’s too late for the onlookers to save him.
 As the floor slab was about to be closed, the onlookers heard Liu Kai mumble:
  “Oh my god-how can I be so careless to install the floor upside down?”
 No matter what you do, don’t be careless. It will go wrong if it is careless. You will pay the price if you are wrong.