Fill in the gaps with the correct words.

A dog is a

... animal. It is the only pet who knows its ... by his voice and even by his appearance. A dog is a good ... and a true friend. It ... your life. It will work for you if you train him. It hunts for you. It plays with you. Dogs belong to a ... of meat-eating animals. They belong to the same family as wolves and foxes. All of the dogs were wild once. But people tamed them, and now dogs are useful to man.