a)

The girl talking to Tom - Девушка разговаривающая с Томом.

The plane flying in the sky - Летящий в небе самолет.

The bird singing in the tree - Поющая на дереве птица..

The rising sun - Восходящее солнце.

The children swimming in the sea - Ребенок плавающий в море.

Factories producing food - Фабрики производящие продукты питания.

People living in towns - Люди живущие в городах.

b)

1) The girl talking to Tom is his sister.

2) There were many clouds and we could not see the rising sun.

3) The bird singing in the tree is not a pigeon, dear.

4) Let's get up early tomorrow and go and watch the plane flying in the sky.

5) The children swimming in the sea were laughing loudly.