问题：
[填空题]Look at the sentences below. They belong to one paragraph, but they are not in the proper order. Put the number 1 after the sentence that should come first (hint: topic sentence). Then, put a 2 after the sentence that should come second, and so on. It might help you to write these out on a piece of paper. Think about the transitions, and how they can help you re-order this text.
For example, a dog could be a beagle that is a family pet.
___
答案解析：