For this accident, the children's father, Mr. Lu believes that the construction site, there is no warning signs, no special care, so there is no effective site security obligations fulfilled.

Unfortunately, the instruction, scrawled in black marker, was the defiant graffiti of a visitor who had decided to mock the plastic sign just above it by saying the same thing.

Placards are social signs that have the social functions of giving directions, warning or advice with certain performative verbs.