The complete sentence with a superlative as indicated is:
SUPERLATIFS - C'est le plus mauvais acteur du film. (= le pire)
Superlatives are known to be a form of adjectives or adverbs that express the highest degree of a quality. They are used to compare three or more things, indicating that one has the most or least of a particular characteristic in a given group.
So, the above le plus mauvais is used because the adjective mauvais is describing the actor's performance compared to the other actors in the film. The superlative form le plus mauvais is used to indicate that the actor's performance is the worst out of all the actors.
Complete each sentence with either a comparative or a superlative as indicated. SUPERLATIFS
C'est __________ acteur du film. ( + mauvais)