question: What star of M0 was a film 's star 's actor
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 ns:film.actor.film/ns:film.performance.character ?x1 .
  ?x0 ns:film.actor.film/ns:film.performance.film M0 .
  ?x1 ns:film.actor.film/ns:film.performance.film ?x2 .
  ?x2 a ns:film.film
  }