instruction: For GEOG 472 last semester , who were the GSIs ?
response: SELECT DISTINCT student.firstname, student.lastname FROM course INNER JOIN course_offering ON course.course_id = course_offering.course_id INNER JOIN gsi ON gsi.course_offering_id = course_offering.offering_id INNER JOIN student ON student.student_id = gsi.student_id INNER JOIN semester ON semester.semester_id = course_offering.semester WHERE course.department = 'GEOG' AND course.number = 472 AND semester.semester = 'FA' AND semester.year = 2015