6.
1) The children are feeding the ducks.
2) Father has bought some ice-cream.
3) Mother is sitting on a bench.
4) Grandfather is eating a sandwich.
5) Grandmother is watching the children.
6) The cat is going to climb a tree.
7) The duck has come out of the lake.
8) A bird is singing in the tree.
7.
1) in
2) between
3) at
4) by
5) on
6) in
7) across
8) on
9) at
10) through