3.I happened____(meet)my old friend in the street yesterday.I____(not see)him for a long time

to meet hadn't seen(=had not seen)
1.happen to do sth 碰巧.
2.很久不见是相对happened to meet 这个特定的过去时点来说的,指的是“过去的过去”,所以用过去完成时但是答案是have not seen错！！！！看我的分析后你还认为原答案对？