题目内容
Sustainable development is applied to just about everything from energy to clean water and economic growth, and as a result it has become difficult to question either the basic assumptions behind it or the way the concept is put to use. This is especially true in agriculture, where sustainable development is often taken as the sole measure of progress without a proper appreciation of historical and cultural perspectives.To start with, it is important to remember that the nature of agriculture has changed markedly throughout history, and will continue to do so. Medieval agriculture in northern Europe fed, clothed and sheltered a predominantly rural society with a much lower population density than it is today. It had minimal effect on biodiversity, and any pollution it caused was typically localized. In terms of energy use and the nutrients captured in the product it was relatively inefficient.Contrast this with farming since the start of the industrial revolution. Competition from overseas led farmers to specialize and increase yields. Throughout this period food became cheaper, safer and more reliable. However, these changes have also led to habitat loss.What’s more, demand for animal products in developing countries is growing so fast that meeting it will require an extra 300 million tons of grain a year by 2050. Yet the growth of cities and industry is reducing the amount of water available for agriculture in many regions.All this means that agriculture in the 21st century will have to be very different from how it was in the 20th. This will require radical thinking. For example, we need to move away from the idea that traditional practices are inevitably more sustainable than new ones. We also need to abandon the notion that agriculture can be "zero impact". The key will be to abandon the rather simple and static measures of sustainability, which centre on the need to maintain production without increasing damage. Instead we need a more dynamic interpretation, one that looks at the pros and cons of all the various ways land is used. There are many different agricultural performances besides food yield: energy use, environmental costs, water purity, carbon footprint and biodiversity. It is clear, for example, that the carbon of transporting tomatoes from Spain to the UK is less than that of producing them in the UK with additional heating and lighting. But we do not know whether lower carbon footprints will always be better for biodiversity. What is crucial is recognizing that sustainable agriculture is not just about sustainable food production. What will agriculture be like in the 21st century（）
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男性，70岁，突发头痛，随即意识丧失，呼之无反应，查体：血压24/15kPa，脉搏60次/分、体温38℃；瞳孔3mm双侧等大、等圆，对光反射迟钝，右侧肢体肌张力Ⅱ级，痛觉反射消失。应用20%甘露醇静脉注射，2～3/次/日，留置尿管。 防止肌肉萎缩的有效护理措施是
When I was young, my parents ran a snack bar in our small town.One evening in early April, my mother told me to fill in at the snack bar (1) a worker who had the flu. I told her I would mess it up, (2) I had never worked at the bar before. I (3) that instead of making money, I would end up owing it."You can do it," said my mother," (4) , you won’t get much business until lunch. ""But I’ll never remember the orders, and I’m no good (5) money. Please, Mom, don’t (6) me."Then I’ll help you", she said.I shrugged my shoulders. I thought my mother’s (7) was a bad one, but I (8) .When I got to the bar the next day, I found my mother was (9) . Because the weather that day was rainy and cold, people wanted hot snacks and drinks. (10) , I was really slow at taking the orders and making change. The line of people grew, and everybody seemed (11) , I was so nervous that my hands shook, and I (12) a cup into pieces. What a mess! Then my mother came to (13) me, and she also showed me how to make (14) . If someone gave me $ 5 for something that cost $ 3.25, I handed over (15) quarters and a dollar and said, "75 cents makes four dollars, plus one dollar makes five. " Things went more (16) after that.By the end of the day, I could remember orders, (17) the bill, and make change quickly with a smile. I was even a little (18) when the sun came out and dried up business. My mother said she was proud of me, and when she (19) that I work at the snack bar again next year, I did not even shrug. I was too busy (20) the restaurant I would open one day. 第（1）空应选择（）
When I was young, my parents ran a snack bar in our small town.One evening in early April, my mother told me to fill in at the snack bar (1) a worker who had the flu. I told her I would mess it up, (2) I had never worked at the bar before. I (3) that instead of making money, I would end up owing it."You can do it," said my mother," (4) , you won’t get much business until lunch. ""But I’ll never remember the orders, and I’m no good (5) money. Please, Mom, don’t (6) me."Then I’ll help you", she said.I shrugged my shoulders. I thought my mother’s (7) was a bad one, but I (8) .When I got to the bar the next day, I found my mother was (9) . Because the weather that day was rainy and cold, people wanted hot snacks and drinks. (10) , I was really slow at taking the orders and making change. The line of people grew, and everybody seemed (11) , I was so nervous that my hands shook, and I (12) a cup into pieces. What a mess! Then my mother came to (13) me, and she also showed me how to make (14) . If someone gave me $ 5 for something that cost $ 3.25, I handed over (15) quarters and a dollar and said, "75 cents makes four dollars, plus one dollar makes five. " Things went more (16) after that.By the end of the day, I could remember orders, (17) the bill, and make change quickly with a smile. I was even a little (18) when the sun came out and dried up business. My mother said she was proud of me, and when she (19) that I work at the snack bar again next year, I did not even shrug. I was too busy (20) the restaurant I would open one day. 第（7）空应选择（）
设常数a＞0，讨论曲线y=ax与曲线y=2lnx的公共点的个数．
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