question: Which actor did M1 , M2 , and M3 star
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:film.actor .
  ?x0 ns:film.actor.film/ns:film.performance.film M1 .
  ?x0 ns:film.actor.film/ns:film.performance.film M2 .
  ?x0 ns:film.actor.film/ns:film.performance.film M3
  }