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在一段时间，各种媒体大量报道了有关疯牛病的消息，“疯牛病”已成为老幼皆知的名词。石老师通过图书馆、科学院和网络，收集了许多关于疯牛病和朊病毒的研究资料，他将在课堂上和同学们一起探讨这个问题。 “为什么国家要严格控制牛肉的进口这说明疯牛病有什么特点” “因为疯牛病会传染，它是一种传染病。”学生不假思索地回答。 “那么哪些病原体会导致传染病呢” 同学们和石老师一起回顾了以往所学到的传染病种类，归纳出病原体有寄生虫、细菌、真菌以及病毒等。石老师没有马上告诉同学们疯牛病的病原体是什么，而是提出了更具挑战性的问题。 “如果有一种原因不明的传染病，如何着手寻找它的病原体呢” 在此之前的生物课中，同学们曾讨论过分离病原体的步骤。石老师希望同学们能够将这一知识应用起来。果然，一个同学想到了解决问题的办法。 “从被感染的动物提取病原体，再用健康动物进行实验。” “很好!”石老师进一步追问：“现在我们要寻找疯牛病的病原体，应该从病牛的哪些部位提取病原体呢” 同学们纷纷提出了自己的看法，有的认为应该抽取血液，有的认为应该从肌肉中提取病原体。这时，石老师向同学们展示了描述疯牛病、疯羊病症状的资料。通过对资料的分析，同学们达成了共识：“疯牛病主要表现为神经系统遭到破坏，最好从神经组织中提取病原体。” 石老师告诉学生，科学家与同学们的选择是一致的。当抽取患病动物的脑组织或脊髓液注射到健康动物后，健康动物最终患病。 接下来，石老师让同学们讨论如何鉴别疯牛病病原体的性质。交流过程中，老师发现一组同学想到了用陶瓷纤维过滤器。在学习病毒的时候，同学们已经了解到陶瓷纤维过滤器可以滤去寄生虫、细菌等，但会让病毒和化合物通过。大家集中对这一方案讨论之后，石老师向同学们展示了科学家实际的实验结果。实验中，未滤过的神经组织和滤过液都可以使健康动物感染该病。石老师又提出了问题： “根据实验结果，我们可以对该病原体的性质和大小做出什么判断呢” “病原体可以通过陶瓷纤维过滤器，说明体积很小，应该是病毒。”一个学生肯定地说。 另一个学生补充说：“经过滤的液体不可能含有细菌、真菌或寄生虫的整体，所以一定是病毒。而且报纸上也说了，是朊病毒导致了疯牛病。” 石老师并不着急纠正同学们的说法，他让同学们考虑一下，能否根据这一项实验结果就断定是病毒会不会还有其他的可能如果你认为是病毒，能不能设计方案进一步证实你的想法 教室里出现了一段时间的沉默。终于，有一个小组的同学提出了他们的假设：“我们可以将滤过液中的病毒破坏，使之不能增殖。再用健康动物实验，如果动物不再患病，说明病原体就是病毒。” “你们准备怎样阻止病毒的增殖呢”石老师追问道。 “只要破坏病毒的DNA或RNA，病毒将不能复制。加热或用福尔马林处理过滤液可以使DNA或RNA变性。” 石老师高度赞扬了这一组同学的设计方案，然后出示了图片。“实际实验的结果是处理后的滤过液仍然具有感染性!这说明了什么” 同学们感到非常吃惊：“看来，实验结果否定了我们的假设。病原体不是病毒!” “病原体还存在于滤过液中，下一步，我们怎样去寻找它呢”石老师继续启发学生。 “滤过液中除了病毒，还有化合物，我们可以鉴定化合物的感染性。” “非常好!”石老师感到很满意，进一步提示：“化合物的种类有很多，我们可以从最基本的生物大分子着手，用什么可以破坏蛋白质、脂肪和淀粉呢” 这个问题对同学们来说很轻松，很快，同学们设计好了一组实验，用不同的酶分别检验这三种大分子化合物。石老师适时地展示出图片，并请同学们对实验结果进行分析。 “原来病原体是一种蛋白质。”同学们高兴地报告自己的结论。 至此，石老师总结：疯牛病的病原体是一种结构改变了的蛋白质，由于这种蛋白质能像病毒一样传播疾病，因而称为“朊病毒”。在石老师的指导下，同学们认识了朊病毒这种新的病原体，了解到朊病毒的蛋白质本质。下课前，石老师还向同学们提供了一些有关朊病毒研究的网址，鼓励有兴趣的同学通过查阅资料对朊病毒有更多的了解。 请根据以上案例，回答下列问题： 石老师在上课前做了充分准备，你认为他在上课前所确立的教学目标有哪些请你简要地写出来。
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TEXT CIn Barcelona the Catalonians call them castells, but these aren’t stereotypical castles in Spain. These castles are made up of human beings, not stone. The people who perform this agile feat of acrobatics are called castellers, and to see their towers take shape is to observe a marvel of human cooperation.First the castellers form what looks like a gigantic rugby scrummage. They are the foundation blocks of the castle. Behind them, other people press together, forming outward-radiating ramparts of inward-pushing muscle: flying buttresses for the castle. Then sturdy but lighter castetlers scramble over the backs of those at the bottom and stand, barefoot, on their shoulders—then still others, each time adding a higher "story".These human towers can rise higher than small apartment buildings: nine "stories", 35 feet into the air. Then, just when it seems this tower of humanity can’t defy gravity any longer, a little kid emerges from the crowd and climbs straight up to the top. Arms extended, the child grins while waving to the cheering crowd far below.Dressed in their traditional costumes, the castellers seem to epitomize an easier time, before Barcelona became a world metropolis and the Mediterranean’s most dynamic city. But when you observe them up close, in their street clothes, at practice, you see there’s nothing easy about what the castellers do—and that they are not merely reenacting an ancient ritual.None of the castellers can give a logical answer as to why they love doing this. But Victor Luna, 16, touches me on the shoulder and says in English: "We do it because it’s beautiful. We do it because we are Catalan."Barcelona’s mother tongue is Catalan, and to understand Barcelona, you must understand two words of Catalan: seny and rauxa. Seny pretty much translates as common sense, or the ability to make money, arrange things, and get things done. Rauxa is reminiscent of our words "raucous" and "ruckus".What makes the castellers revealing of the city is that they embody rauxa and seny. The idea of a human castle is rauxa—it defies common sense—but to watch one going up is to see seny in action. Success is based on everyone working together to achieve a shared goal.The success of Carlos Tusquets bank, Fibanc, shows seny at work in everyday life. The bank started as a family concern and now employs hundreds. Tusquets said it exemplifies how the economy in Barcelona is different.Entrepreneurial seny demonstrates why Barcelona and Catalonia—the ancient region of which Barcelona is the capital—are distinct from the rest of Spain yet essential to Spain’s emergence, after centuries of repression, as a prosperous, democratic European country. Catalonia, with Barcelona as its dynamo, has turned into an economic powerhouse. Making up 6 percent of Spain’s territory, with a sixth of its people, it accounts for nearly a quarter of Spain’s production—everything from textiles to computers—even though the rest of Spain has been enjoying its own economic miracle.Hand in hand with seny goes rauxa, and there’s no better place to see rauxa in action than on the Ramblas, the venerable, tree-shaded boulevard that, in gentle stages, leads you from the centre of Barcelona down to the port. There are two narrow lanes each way for cars and motorbikes, but it’s the wide centre walkway that makes the Ramblas a front-row seat for Barcelona’s longest running theatrical event. Plastic armchairs are set out on the sidewalk. Sit in one of them, and an attendant will come and charge you a small fee. Performance artists throng the Ramblas—stilt walkers, witches caked in charcoal dust, Elvis impersonators. But the real stars are the old women and happily playing children, millionaires on motorbikes, and pimps and women who, upon closer inspection, prove not to be.Aficionados (Fans) of Barcelona love to compare notes: "Last night there was a man standing on the balcony of his hotel room," Mariana Bertagnolli, an Italian photographer, told me, "The balcony was on the second floor. He was naked, and he was talking into a cell phone."There you have it, Barcelona’s essence. The man is naked (rauxa), but he is talking into a cell phone (seny). According to the passage, the implication of the performance is that（）
调查某草原田鼠数量时，在设置1公顷的调查区内放置100个捕鼠笼，一夜间捕获鼠32头，将捕获的鼠经标记后在原地释放。数日后，在同一地方再放置同样数量的捕鼠笼，这次共捕获30头，其中有上次标记过的个体10头。若该地区田鼠种群个体总数为N，N=( )头。
TEXT AAt the age of 16, Lee Hyuk Joon’s life is a living hell. The South Korean 10th grader gets up at 6 in the morning to go to school, and studies most of the day until returning home at 6 p. m. After dinner, it’s time to hit the books again—at one of Seoul’s many so-called cram schools. Lee gets back home at 1 in the morning, sleeps less than five hours, then repeats the routine—five days a week. It’s a grueling schedule, but Lee worries that it may not be good enough to get him into a top university. Some of his classmates study even harder.South Korea’s education system has long been highly competitive. But for Lee and the other 700,000 high-school sophomores in the country, high-school studies have gotten even more intense. That’s because South Korea has conceived a new college-entrance system, which will be implemented in 2008. This year’s 10th graders will be the first group evaluated by the new admissions standard, which places more emphasis on grades in the three years of high school and less on nationwide SAT-style and other selection tests, which have traditionally determined which students go to the elite colleges.The change was made mostly to reduce what the government says is a growing education gap in the country: wealthy students go to the best colleges and get the best jobs, keeping the children of poorer families on the social margins. The aim is to reduce the importance of costly tutors and cram schools, partly to help students enjoy a more normal high-school life. But the new system has had the opposite effect. Before, students didn’t worry too much about their grade-point averages; the big challenge was beating the standardized tests as high-school seniors. Now students are competing against one another over a three-year period, and every midterm and final test is crucial. Fretful parents are relying even more heavily on tutors and cram schools to help their children succeed.Parents and kids have sent thousands of angry online letters to the Education Ministry complaining that the new admissions standard is setting students against each other. "One can succeed only when others fail," as one parent said.Education experts say that South Korea’s public secondary-school system is foundering, while private education is thriving. According to critics, the country’s high schools are almost uniformly mediocre—the result of an egalitarian government education policy. With the number of elite schools strictly controlled by the government, even the brightest students typically have to settle for ordinary schools in their neighbourhoods, where the curriculum is centred on average students. To make up for the mediocrity, zealous parents send their kids to the expensive cram schools.Students in affluent southern Seoul neighbourhoods complain that the new system will hurt them the most. Nearly all Korean high schools will be weighted equally in the college-entrance process, and relatively weak students in provincial schools, who may not score well on standardized tests, often compile good grade-point averages.Some universities, particularly prestigious ones, openly complain that they cannot select the best students under the new system because it eliminates differences among high schools. They’ve asked for more discretion in picking students by giving more weight to such screening tools as essay writing or interviews.President Roh Moo Hyun doesn’t like how some colleges are trying to circumvent the new system. He recently criticized "greedy" universities that focus more on finding the best students than trying to "nurture good students". But amid the crossfire between the government and universities, the country’s 10th graders are feeling the stress. On online protest sites, some are calling themselves a "cursed generation" and "mice in a lab experiment". It all seems a touch melodramatic, but that’s the South Korean school system. According to the passage, there seems to be disagreement over the adoption of the new system between the following groups EXCEPT（）
小麦植株最上一片叶称为旗叶，它对小麦籽粒的产量起着决定性的作用。与这种功能关系最密切的结构特点是下面哪些( ) ①细胞排列紧密 ②细胞中叶绿体数目较多 ③细胞中线粒体较多 ④叶绿体中基粒内类囊体数目多 ⑤细胞中具有中心体
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