question: Who did M1 and M2 star , M3 star , and a film star
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 a ns:people.person .
  ?x0 ns:film.actor.film/ns:film.performance.film ?x1 .
  ?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 .
  ?x1 a ns:film.film
  }