1987年10月，美国股票市场遭受了一次大的价格下跌。在下跌后的几周里，股票的交易量也剧烈下降，大大低于前一年平均周交易量。但是，这一整年的交易量与前一年的交易量并没有明显差异。 以下哪项，如果正确，能最好地解释上面短文中提出的明显矛盾？（）
A．外国投资者通常只有在价格低的时候才购买美国股票。
B．1987年的股票购买者人数与前一年人数大致相同。
C．1987年的某一段时间，股票交易量高于那一年的平均交易量。
D．某一年股票的交易量越大，则美国股票市场该年每股的平均价格就越低。
E．股票交易量以可预测的周期形式涨落。
点击查看答案
在pH=10的溶液中,用EDTA滴定液测定Mg 2+ ,可选用的指示剂是( )。(1.0分)
A. 铬黑T B. 二甲酚橙 C. 酚酞 D. 甲基橙
点击查看答案
How science goes wrong Scientific research has changed the world. Now it needs to change itself.[A] A simple idea underlies science: "trust, but verify". Results should always be subject to challenge from experiment. That simple but powerful idea has generated a vast body of knowledge. Since its birth in the 17th century, modern science has changed the world beyond recognition, and overwhelmingly for the better. But success can breed extreme self-satisfaction. Modern scientists are doing too much trusting and not enough verifying, damaging the whole of science, and of humanity.[B] Too many of the findings are the result of cheap experiments or poor analysis. A rule of thumb among biotechnology venture-capitalists is that half of published research cannot be replicated (复制). Even that may be optimistic. Last year researchers at one biotech firm, Amgen, found they could reproduce just six of 53 "milestone" studies in cancer research. Earlier, a group at Bayer, a drug company, managed to repeat just a quarter of 67 similarly important papers. A leading computer scientist worries that three-quarters of papers in his subfield are nonsense. In 2000-10, roughly 80,000 patients took part in clinical trials based on research that was later withdrawn because of mistakes or improperness.What a load of rubbish[C] Even when flawed research does not put people’s lives at risk—and much of it is too far from the market to do so—it blows money and the efforts of some of the world’s best minds. The opportunity costs of hindered progress are hard to quantify, but they are likely to be vast. And they could be rising.[D] One reason is the competitiveness of science. In the 1950s, when modern academic research took shape after its successes in the Second World War, it was still a rarefied (小众的) pastime. The entire club of scientists numbered a few hundred thousand. As their ranks have swelled to 6m-7m active researchers on the latest account, scientists have lost their taste for self-policing and quality control. The obligation to "publish or perish (消亡)" has come to rule over academic life. Competition for jobs is cut-throat. Full professors in America earned on average $135,000 in 2012—more than judges did. Every year six freshly minted PhDs strive for every academic post. Nowadays verification (the replication of other people’s results) does little to advance a researcher’s career. And without verification, uncertain findings live on to mislead.[E] Careerism also encourages exaggeration and the choose-the-most-profitable of results. In order to safeguard their exclusivity, the leading journals impose high rejection rates: in excess of 90% of submitted manuscripts. The most striking findings have the greatest chance of making it onto the page. Little wonder that one in three researchers knows of a colleague who has polished a paper by, say, excluding inconvenient data from results based on his instinct. And as more research teams around the world work on a problem, it is more likely that at least one will fall prey to an honest confusion between the sweet signal of a genuine discovery and a nut of the statistical noise. Such fake correlations are often recorded in journals eager for startling papers. If they touch on drinking wine, or letting children play video games, they may well command the front pages of newspapers, too.[F] Conversely, failures to prove a hypothesis (假设) are rarely even offered for publication, let alone accepted. "Negative results" now account for only 14% of published papers, down from 30% in 1990. Yet knowing what is false is as important to science as knowing what is true. The failure to report failures means that researchers waste money and effort exploring blind alleys already investigated by other scientists.[G] The holy process of peer review is not all it is praised to be, either. When a prominent medical journal ran research past other experts in the field, it found that most of the reviewers failed to spot mistakes it had deliberately inserted into papers, even after being told they were being tested.If it’s broke, fix it[H] All this makes a shaky foundation for an enterprise dedicated to discovering the truth about the world. What might be done to shore it up One priority should be for all disciplines to follow the example of those that have done most to tighten standards. A start would be getting to grips with statistics, especially in the growing number of fields that screen through untold crowds of data looking for patterns. Geneticists have done this, and turned an early stream of deceptive results from genome sequencing (基因组测序) into a flow of truly significant ones.[I] Ideally, research protocols (草案) should be registered in advance and monitored in virtual notebooks. This would curb the temptation to manipulate the experiment’s design midstream so as to make the results look more substantial than they are. (It is already meant to happen in clinical trials of drugs.) Where possible, trial data also should be open for other researchers to inspect and test.[J] The most enlightened journals are already showing less dislike of tedious papers. Some government funding agencies, including America’s National Institutes of Health, which give out $30 billion on research each year, are working out how best to encourage replication. And growing numbers of scientists, especially young ones, understand statistics. But these trends need to go much further. Journals should allocate space for "uninteresting" work, and grant-givers should set aside money to pay for it. Peer review should be tightened—or perhaps dispensed with altogether, in favour of post-publication evaluation in the form of appended comments. That system has worked well in recent years in physics and mathematics. Lastly, policymakers should ensure that institutions using public money also respect the rules. [K] Science still commands enormous—if sometimes perplexed—respect. But its privileged status is founded on the capacity to be right most of the time and to correct its mistakes when it gets things wrong. And it is not as if the universe is short of genuine mysteries to keep generations of scientists hard at work. The false trails laid down by cheap research are an unforgivable barrier to understanding.
点击查看答案
叠加通行费的隧道指装有通风和监控设施的独立隧道（含左右洞），按长度分1000-2500米、2500-4000米、4000-5500米、5500-7000米、7000-8500米、8500-10000米、10000米以上七类，分别叠加（）辆/次。
A.1元、2元、5元、8元、10元、12元、15元
B.2元、3元、5元、7元、10元、12元、15元
C.1元、3元、5元、8元、10元、12元、15元
D.1元、2元、4元、5元、7元、10元、12元
点击查看答案
题目内容
（请给出正确答案）
参考答案
十点题库官方参考答案
（由十点题库聘请的专业题库老师提供的解答）
