question: Was M0 a Canadian employee of M1 , M2 , and M3
query: SELECT count(*) WHERE {
  M0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
  M0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
  M0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
  M0 ns:people.person.nationality ns:m.0d060g
  }