73.1:
2)that house
3)these postcards
4)those birds
5)this seat
6)these plates
73.2:
2)Is that your umbrella?
3)Is this your book?
4)Are those your books?
5)Is that your bicycle?
6)Are these your keys?
7)Are those your keys?
8)Is this your watch?
9)Are those your glasses?
10)Are these your gloves?
73.3:
2)that's
3)this is
4)that's
5)that
6)this is
7)that's
8)that's