Who did M1 employ , M2 employ , and M3 , M4 , M5 , M6 , and M7 employ
SELECT DISTINCT ?x0 WHERE {
?x0 a ns:people.person .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M1 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M2 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M3 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M4 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M5 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M6 .
?x0 ns:people.person.employment_history/ns:business.employment_tenure.company M7
}