what do you mean there are only ten tickets ther - be twelve

这里是should 本应该的意思
译文：你说本来有10张票却有12张,
参考：
shall
1.将要,一般将来时,用于主语是第一人称的时候 I shall...或者we shall...
2.应该,较少用,基本上可以不用就不用.
should
1.将要shall的过去时 ,用法同shall
2.“应该”,主语随便是第一二三人称,都可以,较常用.
will 将要,一般将来时用 He will go on studying after graduation.
would
1.将要,过去将来时,He would go on studying when he had graduated.
2.过去常常会 He would go fishing at that time.他那时经常去钓鱼.
3 I would like.