teacher
a person who teaches students /ˈtiː.tʃər/
doctor
a person who helps sick people /ˈdɒk.tər/
nurse
a person who helps in a hospital /nɜːs/
police officer
a person who keeps people safe /pəˈliːs/
Examples
"My teacher is very kind."
"I need to see a doctor."
"The nurse gave me medicine."
"The police officer helped us."