Boonjour,
Réponse :
a. the knight/must/his king/defends/defend
The knight must defend his King.
b.be/ the story/must/is/funny/.
The story must be funny.
c. you choose / mustn't/ don't/ violent characters /
You mustn't choose violent characters.
Explications :
must /mustn't sont suivis d'une base verbale ( infinitif sans "to" )
