题目内容
某16位计算机中，带符号整数用补码表示，数据Cache和指令Cache分离。表1给出了指令系统中部分指令格式，其中Rs和Rd表示寄存器，mem表示存储单元地址，(x)表示寄存器x或存储单元x的内容。 该计算机采用5段流水方式执行指令，各流水段分别是取指IF、译码/读寄存器ID、执行/计算有效地址EX、访问存储器M、结果写回寄存器WB，流水线采用“按序发射，按序完成”方式，没有采用转发技术处理数据相关，并且同一寄存器的读和写操作不能在同一个时钟周期内进行。请回答下列问题。 表1 指令系统中部分指令格式名 称指令的汇编格式指令功能加法指令ADD Rs，Rd(Rs)+(Rd)→Rd算术左移SHL Rd2*(Rd)→Rd算术右移SHR Rd(Rd)/2→Rd取数指令LOAD Rd，mem(mem)→Rd存数指令STORE Rs，mem(Rs)→mem 若高级语言程序中某赋值语句为x=2*x+a，x和a均为unsigned int型变量，它们的存储单元地址分别表示为[x]、[a]。执行这条语句至少需要多少个时钟周期要求模仿表2画出这条语句对应的指令序列及其在流水线中的执行过程示意图。
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设有抛物线L：y=a-bx2，试确定常数a，b的值，使得 (Ⅰ)L与直线y=x+1相切； (Ⅱ)L与x轴所围图形绕y轴旋转所得旋转体的体积最大。
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Text 1 Every Saturday morning, at 9 am, more than 50,000 runners set off to run 5km around their local park. The Parkrun phenomenon began with a dozen friends and has inspired 400 events in the UK and more abroad. Events are free, staffed by thousands of volunteers. Runners range from four years old to grandparents; their times range from Andrew Baddeley’s world record 13 minutes 48 seconds up to an hour. Parkrun is succeeding where London’s Olympic "legacy" is failing. Ten years ago on Monday, it was announced that the Games of the 30th Olympiad would be in London. Planning documents pledged that the great legacy of the Games would be to level a nation of sport lovers away from their couches. The population would be fitter, healthier and produce more winners. It has not happened. The number of adults doing weekly sport did rise, by nearly 2 million in the run-up to 2012-but the general population was growing faster. Worse, the numbers are now falling at an accelerating rate. The opposition claims primary school pupils doing at least two hours of sport a week have nearly halved. Obesity has risen among adults and children. Official retrospections continue as to why London 2012 failed to "inspire a generation." The success of Parkrun offers answers. Parkun is not a race but a time trial: Your only competitor is the clock. The ethos welcomes anybody. There is as much joy over a puffed-out first-timer being clapped over the line as there is about top talent shining. The Olympic bidders, by contrast, wanted to get more people doing sports and to produce more elite athletes. The dual aim was mixed up: The stress on success over taking part was intimidating for newcomers. Indeed, there is something a little absurd in the state getting involved in the planning of such a fundamentally "grassroots", concept as community sports associations. If there is a role for government, it should really be getting involved in providing common goods-making sure there is space for playing fields and the money to pave tennis and netball courts, and encouraging the provision of all these activities in schools. But successive governments have presided over selling green spaces, squeezing money from local authorities and declining attention on sport in education. Instead of wordy, worthy strategies, future governments need to do more to provide the conditions for sport to thrive. Or at least not make them worse. The author’s attitude to what UK governments have done for sports is_____.
Text 4 Though often viewed as a problem for western states, the growing frequency of wildfires is a national concern because of its impact on federal tax dollars, says Professor Max Moritz, a specialist in fire ecology and management. In 2015, the US Forest Service for the first time spent more than half of its $5.5 billion annual budget fighting fires-nearly double the percentage it spent on such efforts 20 years ago. In effect, fewer federal funds today are going towards the agency’s other work-such as forest conservation, watershed and cultural resources management, and infrastructure upkeep-that affect the lives of all Americans. Another nationwide concern is whether public funds from other agencies are going into construction in fire-prone districts. As Moritz puts it, how often are federal dollars building homes that are likely to be lost to a wildfire "It’s already a huge problem from a public expenditure perspective for the whole country," he says. We need to take a magnifying glass to that. Like, "Wait a minute, is this OK" "Do we want instead to redirect those funds to concentrate on lower-hazard parts of the landscape" Such a view would require a corresponding shift in the way US society today views fire, researchers say. For one thing, conversations about wildfires need to be more inclusive. Over the past decade, the focus has been on climate change-how the warming of the Earth from greenhouse gases is leading to conditions that worsen fires. While climate is a key element, Moritz says, it shouldn’t come at the expense of the rest of the equation. "The human systems and the landscapes we live on are linked, and the interactions go both ways," he says. Failing to recognize that, he notes, leads to "an overly simplified view of what the solutions might be. Our perception of the problem and of what the solution is becomes very limited." At the same time, people continue to treat fire as an event that needs to be wholly controlled and unleashed only out of necessity, says Professor Balch at the University of Colorado. But acknowledging fire’s inevitable presence in human life is an attitude crucial to developing the laws, policies, and practices that make it as safe as possible, she says. "We’ve disconnected ourselves from living with fire," Balch says. "It is really important to understand and try and tease out what is the human connection with fire today." Professor Balch points out that fire is something man should _____.
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