with t1 as( select t1.emp_id, exam_id, emp_level, submit_time-start_time as answer_time, score from emp_info t1 inner join exam_record t2 on t1.emp_id = t2.emp_id where emp_level < 7 ), t2 as( select exam_id, avg(submit_time-start_time) as avg_answer_time, avg(score) as avg_score from exam_record...