Direction: In the following passage, some of the words have been left out. First read the passage over and try to understand what it is about. Then fill in the blanks with the help of the alternatives given.

Ants play an important part in the __471__ of nature. They eat a large __472__of insects and so help keep them __473__ becoming too plentiful. In the tropics, ants eat more __474__
half the termites hatched each year. Ants, in __475__ are an important __476__ source for birds. Frogs, lizards and many other animals also feed __477__ ants. Ants are __478__ helpful and harmful to farmers. Some kinds of ants aid farmers by killing insects that __479__ crops. Ants that dig underground nests __480__ the soil. They break up, loosen and mix the soil.