question: Which Canadian star of M1 did M2 star
query: SELECT DISTINCT ?x0 WHERE {
  ?x0 ns:film.actor.film/ns:film.performance.film M1 .
  ?x0 ns:film.actor.film/ns:film.performance.film M2 .
  ?x0 ns:people.person.nationality ns:m.0d060g
  }