1 ) It is his souvenir . The souvenir is
HIS.
2 ) They are her flowers . The flowers are HERS.
3 ) It is their castle . The castle is THEIRS.
4 ) It is my diary . The diary is MINE.
5 ) They are our boats . The boats are OURS.
6 ) They are your postcards . The postcards are YOURS.