From the picture, Men who wear blue trousers are slippery because the ground is filled with yellow water that wet on the floor. He did not see a warning sign above on the door. The man standing behind only stand and look at this man is slippery. If he can see the warning signs. He may avoid walking through this area. and he will not be harmed. Therefore, there should be a warning sign can be seen clearly. In order to prevent the accident.