"should(ought to)+have+p.p.表示“应该发生而没有发生的事情”。"中“p.p.”是什么意思啊？

过去分词，如should have done

解答情态动词表示猜测的试题时,一要清楚被猜测的时间,二要清楚有无客观事实根据.若有客观事实根据,则无论是肯定还是否定的猜测,猜测语气最强且符合时间要求的为最佳答案;情态动词表示猜测时语气从强到弱的顺序是:must,will,would,ought to,should,can,may,could,might.若无客观事实根据,纯凭主观臆断,则猜测语气最弱且符合时间要求的为最佳答案.如:
1.I thought you __________ like something to read,so I have brought you some books.(MET 1986)
A.may B.might
C.could D.must
由题意可知被猜测的时间是(过去)将来,没有客观事实根据,猜测语气要求最弱,所以正确选项是B.
2.Peter __________ come with us tonight,but he isn't sure yet.(MET 1993)
A.must B.may
C.can D.will
由题意可知被猜测的时间是将来,没有客观事实根据,猜测语气要求最弱,所以正确选项是B.
3.It __________ last night,for the ground was wet this morning.
A.must have rained
B.may have rained
C.must rain
D.might rain
由题意可知被猜测的时间是过去,有客观事实根据the ground was wet,猜测语气要求最强,所以正确选项是A.
4.Mary __________ be in Paris,for I saw her in the town only a few minutes ago.(MET 1994)
A.mustn't B.can't
C.shouldn't D.may not
由题意可知被猜测的时间是现在,有客观事实