垃圾的分类The classification of garbageHello, everyone! I am glad to have this chance to share some ideas about the classification of garbage with you.When walking in the campus, you usually ask yourself，“where is the garbage can?”，in order to lose rubbish in your hand. In the past, I think it is a fairly easy thing to throw rubbish. The only thing which waste my time is to find a garbage can in the nearby. Then I would throw the garbage into the trash can with giving a whistle.But now things are changing. Along with the environmental policy，I find that more and more garbage can with novel style appeare in the campus. They ordinarily consist of two parts. One used to hold the recyclable garbage, and another used to store unrecyclable garbage. So when I’m ready to throw rubbish, I need to stop and think. What type of garbage does it belong to in my hand? Recyclable? Unrecyclable? Then I must to bent down to see what is written on the barrel. Which one is recyclable barrel? Which one is unrecyclable barre l? Because I’m nearsighted. Although this process wastes my some time, when I put the rubbish into the right position, I will arise spontaneously a sense of achievement. Because I think I have done a little useful thing for the great cause of environmental protection.But sometimes ,it is not a simple thing to make sure the type ofgarbage in my hand. For the same piece of paper, it belongs to different garbage classification in different situations. If it is a clean piece of paper, it belongs to recycle garbage without doubt. When I write on the paper, or fold the paper, I still can easily know it belongs to recycled garbage. But how about this? (sneeze, blowing my nose, chewing gum). Do you still insist that it is recycled rubbish? I believe that most peop le don’t. Specifically, this answer is not correct either. In the garbage classification, it belongs to the combustible rubbish or organic waste. For the other one example, when you want to throw away the leftover breakfast, how do you deal with it? Is it recycled? Is it unrecyclable? Or not all. Because the leftover breakfast belongs to kitchen waste.Next, let’s look at the specific classification of garbage. As we can see, the consumer, mainly produces four kinds of rubbish in our daily life. They are recyclable, unrecyclable, combustible, and kitchen waste. For the unrecyclable, the main way to deal with it is landfill. It takes up a lot of land and pollute them. However, if we adopt the right technology to it, the unrecyclable garbage can be converted to methane which is useful for us. For the recyclable garbage, they are often used to recycle, and produce recycled goods. And how about combustible rubbish? Just as its name implies, the main way to deal with it is burning. The energy of burning is used to generate electricity which provide security for the life. Next for the kitchen waste, it is very appropriate to organic compost.Organic fertilizers is a kind of environmentally friendly fertilizers. So in the end, the garbage is reused in various other ways and come back to our life. This is a very valuable cycle.For example, how to deal with waste batteries? If there is only one or a little ordinary battery, you can throw it and living garbage together. Because the battery with mercury do little harm to the environment. Recommended not to collect the battery, and not plan to thrown away when you think it. Because you may forget it. A lot of batteries have greater pollution. If you have many batteries is in need of treatment, please put it to correct position. Our school has a special garbage can to recycling battery.So now the garbage classification is not perfect, but it is very helpful to built up our consciousness of garbage classification. You might ask, “Is there a simple method which can quickly classify rubbish?” Sorry, I can’t give this method. Because garbage classification depends on each person’s value judgement. But you can give the rubbish to the garbage m an in your dormitory and ask, “How much does they value?” If he take the garbage and give you some money, it means the garbage is recycled. If he gives you a glimpse and say, “go away!” It means the garbage is unrecyclable.So I support the garbage classification policy. Many people side and I are also to do so. I usually take some times to divide garbage into twoparts. This part is recycled garbage. That part is unrecyclable garbage. Then I put them into correct position. But in the end, what happened? I see the garbage to be put together once again! Are you kitting me?This is a question to make me feel puzzled. It make me become negative to classify garbage. What is the practical significance of garbage classification? The new style of garbage can is not only used to enjoy. We need do more thing!Thanks! 圆柱表面积练习题一、填空1、把圆柱体的侧面展开，得到一个（），它的（）等于圆柱底面周长，（）等于圆柱的高．2、一个圆柱体，底面周长是94.2厘米，高是25厘米，它的侧面积是（）平方厘米．3、一个圆柱体，底面半径是2厘米，高是6厘米，它的侧面积是（）平方厘米．4、一个圆柱体的侧面积是12.56平方厘米，底面半径是2分米，它的高是（）厘米．5、把一张长8分米，宽5分米的白纸，围成一个圆柱形纸筒，这个纸筒的侧面积是（）平方分米．6、把一张边长为5.5厘米的正方形白纸，围成一个圆柱形纸筒，这个纸筒的侧面积是（）平方分米．二、判断1、圆柱的侧面展开后一定是长方形．（）2、6立方厘米比5平方厘米显然要大．（）3、一个物体上、下两个面是相等的圆面，那么，它一定是圆柱形物体．（）4、把两张相同的长方形纸，分别卷成两个形状不同的圆柱筒，并装上两个底面，那么制的圆柱的高、侧面积、表面积一定相等．（）三、求下面各圆柱体的侧面积．1、底面周长是6分米，高是3.5分米．2、底面直径是2.5分米，高是4分米．3、底面半径是3厘米，高是15厘米．四、判断1、圆柱体的表面积＝底面积×2＋底面积×高．（）2、圆柱体的表面积一定比它的侧面积大．（）3、圆柱体的高越长，它的侧面积就越大．（）4、圆柱的高与底面直径相等，它的侧面展开图是正方形。