When you plant a seed (种子)，does it stay a seed? No! Plants and animals grow and (改变) in their lives. Many plants begin as seeds. When the seed gets (水) and sunlight, it begins to grow. The seed turns into a (小的）plant and grows up. Then the plant makes new seeds. (那些) seeds go through this over and over again，it is called a life cycle (循环).
Animals (也) have life cycles. A bird begins as an egg. And then it grows legs and (手臂）inside. When the egg breaks up，a bird is (出生）and then grows up day by day. After that, the bird lays eggs, so new birds can live even after the mother bird grows old and (死).
A dog's life cycle isn't the (相同的）as a bird's，because a dog does not start out as an egg. The dog keeps growing and (最后）becomes a big dog. Then the dog might have babies to start the life cycle again! Don't you think it is interesting to see the magic world?
