we all remember the days --- we studied together at school H

we all remember the days ___ we studied together at school He still remembers the days _____he sprnwe all remember the days ___ we studied together at schoolHe still remembers the days _____he spent with your familly.A when B where C that D on which1.when 2.C我觉得两个题题型都相同啊,为何答案不同