Answer:
1:A traffic enforcer is using the stop sign to stop vehicles for the children who's crossing the road
2:A caution sign is placed on Dangerous places to warn trespassers
3: An electrician places a high voltage sign on the electric tower to warn people of electricution
4:A chemist placed a sign reminding people to wear their safety goggles
5:A librarian placed the sign to inform students not to read while walking
