Database Management System - Old Questions

2. What do you mean by weak entity and partial key? Design an ER diagram for following scenario;  [3+7]

In film industry, producers produce movies. Producers have their name, age and budget as attributes. They are uniquely identified by prod_id. All the movies have their title, year, and release date. No movies can have same title. Every movies must be played by actor. An actor can play many movies. Actors have Fname and Lname to uniquely identify them. The actors have charge_rate as well. A single movie can have many producers and a producer can produce many movies.