Penguins(企鹅) live together in large and busy colonies. Every pair has a little piece of ground. When a penguin wants to walk through his neighbor's ground he must ask permission. If he does not, he will have to fight. Penguins come and go all day. They fight and look after their children. All penguins are good parents and the Emperor penguins are perhaps the best parents in the world. They walk in from the sea in the middle of the dark Antarctic winter. They choose their wives in the dark. They can only hear them -- not see them. Then the females lay their eggs. The males hold them on their feet inside a fold of skin. If the eggs get cold there will be no chicks. There is no food. The snow falls. The wind blows sometimes at 150 kilometers an hour. The penguins do not move. When the females return from the sea they will not remember their husbands. It does not matter. Only one thing matters -- the eggs. Emperor penguins never fight -- unless a penguin leaves a chick for a minute. Then they fight because they all want it. They are strange and wonderful birds. Each pair of penguins lives together with ______.