小丁丁计算时，把减数25错写成45，算出的差是30，这题的正确算式应是____-25=____。

）向炭粉、Cu和Fe₂O₃组成的混合粉末中加入一定量的稀硫酸，充分反应后过滤，得到溶液A，将沉淀物洗涤、干燥，得到固体B．

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    Green is not always referring to the color. In some cases, it is the term used for environmental____(friend). If you've been expecting to replace your furniture, consider ____(go) green because green furniture offers many benefits. Here are a few tips to get you started on your hunt for the perfect eco-friendly furniture.

    First, green furniture isn't harmful____your health. Also its making process doesn't cause damage to the environment in any way. Besides, by using eco-friendly ____(product), you prevent global warming to some degree in your own way.

    The materials____are used in furniture are what make them green. Materials can be good for the environment ____ because they are renewable resources or they are all ____(nature). A lack of chemicals in furniture also____(mean) it is a better choice for the environment. It may be hard to imagine that a sofa or a table could actually be____green product, but they really can be depending on what they ____(make)of.

    Therefore, when you want to hunt for the perfect green furniture, you should choose the green materials.

下列是家兔和狼的牙齿结构示意图，据图回答：

1、图一是____ 的牙齿，判断依据是口腔内没有结构____ （填序号和名称），该种牙齿的作用是____ 。兔和狼的牙齿的分化是与它们的____ 相适应的。
2、图一中的结构____ 与图二中的结构____ 的功 能一样，都是咀嚼食物。