题目内容：
EAs more people move into apartments, there are limitations on keeping of animals like dogs and monkeys. Therefore, caged animals have increased in popularity. Birds fall into this group. We keep them for their beautiful songs and feathers. Fish-keeping is a widespread hobby and the keeper can observe their behaviour in the glass tank and study its entire life cycle. The cat is a fine house pet and it fits neatly into human habitation(居住地) without requiring its own cage. They are wonderful hunters, if there are rats around.
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