Teacher - school - teach students
farmer - farm - grow vegetables
greengrocer - greengrocer's - sell fruit and vegetables
postman - post office - take letters to people
waiter - café - serve people
A teacher works at school. He teaches students.
A farmer works in a farm. He grows vegetables.
A green grocer works in a greengrocer's. He sells fruit and vegetables.
A postman works in a post office. He takes letters to people.
A waiter works in a café. He serves people.