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在窗体上添加一个名称为Command1的命令按钮，然后编写如下事件代码： Private Sub Command1_Click() A=75 If a＜60 Then x=1 If a＜70 Then x=2 If a＜80 Then x=3 If a＜90 Then x=4 MsgBox x End Sub 运行窗体，单击命令按钮，则消息框的输出结果是( )。
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In 1998 consumers could purchase virtually anything over the Internet. Books, compact discs, and even stocks were available from World Wide Web Sites that seemed to spring up almost daily. A few years earlier, some people had predicted that consumers accustomed to shopping in stores would be reluctant to buy things that they could not see or touch in person. For a growing number of time-starved consumers, however, shopping from their home computer was proving to be a convenient alternative to driving to the store. A research estimated that in 1998 US consumers would purchase $ 7.3 billion of goods over the Internet, double the 1997 total. Finding a bargain was getting easier, owing to the rise of online auctions and Web sites that did comparison shopping on the Internet for the best deal. For all the consumer interest, retailing in cyberspace was still a largely unprofitable business, however. Internet pioneer Amazon. com, which began selling books in 1995 and later branched into recorded music and videos, posted revenue of $153.7 million in the third quarter, up from $37.9 minion in the same period of 1997. Overall, however, the company’s loss widened to $45.2 million from $9.6 million, and analysts did not expect the company to turn a profit until 2001. Despite the great loss, Amazon. com had a stock market value of many billions, reflecting investors’ optimism about the future of the industry. Internet retailing appealed to investors because it provided an efficient means for reaching millions of consumers without having the cost of operating conventional stores with their armies of salespeople. Selling online carried its own risks, however. With so many companies competing for consumers’ attention, price competition was intense and profit margins thin or nonexistent. One video retailer sold the hit movie Titanic for $9.99, undercutting the $19.99 suggested retail price and losing about $6 on each copy sold. With Internet retailing still in its initial stage; companies seemed willing to absorb such losses in an attempt to establish a dominant market position. Finding a bargain on the Internet was getting easier partly because______.
(46) U.S. farmers are planting more acres of crops using soil building and pollution fighting faming systems than traditional methods that rely on the plow or intensive tillage, according to a report due to be released early next month.The report, titled "National Crop Residue Management Survey," shows a 6 million acre gain for environmentally friendly farming systems this year.(47) It also shows traditional farming methods, which result in greater soil erosion and run off from fields, declined by 4 million acres.(48) The survey, conducted on a county-by-county basis by USDA Natural Resources Conservation Service, indicates that farmers in Iowa, Illinois, South Dakota, Kansas, and Indiana contributed the most to the increase in acres grown with environmentally friendly farming systems known as conservation tillage systems.These states accounted for 5 million of the 6 million acre increase in conservation tillage this year.All conservation tillage systems, such as no-till, mulch-till, ridge-till, strip-till, and zone-till, rely on less tillage or less soil disturbance to plant and manage crops.Farmers who use these systems leave plant materials stems, stalks, and leaves—on the surface of fields after harvest.The plant materials, also called crop residues, serve as a blanket to protect the soil from erosion.The crop residues slowly decompose to add organic matter to the soil much like mulching or composting add organic matter to a garden.The survey results for 1997 indicate that conservation tillage systems now account for 109.8 million acres or fully 37 percent of the 294.6 million annually planted cropland acres in the United States.In the meantime, traditional systems that rely on the plow or intensive tillage fell to 107.6 million acres this year.The remaining acres are in an intermediate farming system known as reduced till.(49) The head of the nonprofit center that compiles and publishes the annual survey is calling on consumers and farmers alike to focus increased attention on conservation tillage systems."(50) Independent research and practical application across the country show that these systems not only replenish and build organic matter in the soil for improved fu ture food productivity but they will also protect water quality and enhance wild life and the environment for future generations," says John Hebblethwaite, executive director of the Conservation Technology Information Center. "There is also growing evidence that these systems can even help us combat the potential for global warming," he adds.Conservation tillage has long been credited for protecting water quality by reducing runoff from farm fields, according to Hebblethwaite.He notes the latest research also indicates that soil enriched by crop residues offers natural protection for groundwater.Conservation tillage systems save the farmer money by reducing trips through the field for planting and cultivation. 50
[A] Communication makes both party know more about each other which make an agreement.[B] The argument itself can not expand knowledge.[C] Reasonable debate plays a postive role in knowledge adrances[D] A basic common knowledge mabe contribution to the argument from which people learn something.[E] Generally, knowledge is gained by argument.[F] Learning can be interrupted by the argument.Do we learn more from people whose views we share in common than from those whose ideas contradictors The speaker claims so, for the reason that disagreement can cause stress and inhabit learning. I concede that undue discord can impede learning. Otherwise, in my view we learn far from discourse and debate with those whose ideas we oppose than from people whose ideas are in accord with our own.41.______Admittedly, under some circumstances disagreement with others can be counterproductive to learning. For supporting examples, one need look no further than a television set. On today’s typical television or radio talk show, disagreement usually manifests itself in meaningless rhetorical bouts and shouting matches, during which opponents vie to have their own message heard, but have little interest either in finding any common ground with or in acknowledging the merits of the opponent’s viewpoint. Understandably, neither the combatants nor the viewers learn anything meaningful. In fact, these battles only serve to reinforce the predispositions and biases of all concerned. The end result is that learning is impeded.42.______Disagreement can also inhibit learning when two opponents disagree on fundamental assumptions needed for meaningful discourse and debate. For example, a student of paleontology learns little about the evolution of an animal species under current study by debating with an individual whose religious belief system precludes the possibility of evolution to begin with. And, economics and finance students learn little about the dynamics of a laissez-faire system by debating with a socialist whose view is that a centralized power should control all economic activity.43.______Aside from the foregoing two provisions, however, I fundamentally disagree with the speaker’s claim. Assuming common ground between two rational and reasonable opponents willing to debate on intellectual merits, both opponents stand to gain much from that debate. Indeed it is primarily through such debate that human knowledge advances, whether at the personal, community, or global level.44.______At the personal level, by listening to their parents’ rationale for their seemingly oppressive rules and policies, teenagers can learn how certain behaviors naturally carry certain undesirable consequences. At the same time, by listening to their teenagers concerns about autonomy and about peer pressures parents can learn the valuable lesson that effective parenting and control are two different things. At the community level, through dispassionate dialogue an environmental activist can come to understand the legitimate economic concerns of those whose jobs depend on the continued profitable operation of a factory. Conversely, the latter might stand to learn much about the potential public-health price to be paid by ensuring job growth and a low unemployment rate. Finally, at the global level , two nations with opposing political or economic interests can reach mutually beneficial agreements by striving to understand the other’s legitimate concerns for its national security, its political sovereignty, the stability of its economy and currency, and so forth.45.______In sum, unless two opponents in a debate are each willing to play on the same field and by the same rules, I concede that disagreement can impede learning. Otherwise, reasoned discourse and debate between people with opposing viewpoints is the very foundation upon which human knowledge advances. Accordingly, on balance the speaker is fundamentally correct. 45
SoBig. F was the more visible of the two recent waves of infection because it propagated itself by e-mail, meaning that victims noticed what was going on. SoBig. F was so effective that it caused substantial disruption even to those protected by anti-virus software. That was because so many copies of the virus spread (some 500,000 computers were infected) that many machines were overwhelmed by messages from their own anti-virus software. On top of that, one common counter-measure backfired, increasing traffic still further. Anti-virus software often bounces a warning back to the sender of an infected e-mail, saying that the e-mail in question cannot be delivered because it contains a virus, soBig. F was able to spoof this system by "harvesting" e-mail addresses from the hard disks of infected computers. Some of these addresses were then sent infected e-mails that had been doctored to look as though they had come from other harvested addresses. The latter were thus sent warnings, even though their machines may not have been infected. Kevin Haley of Symantec, a firm that makes anti-virus software, thinks that one reason SoBig. F was so much more effective than other viruses that work this way is because it was better at searching hard-drives for addresses. Brian King, of CERT, an internet-security centre at Carnegie-Mellon University in Pittsburgh, notes that, unlike its precursors, SoBig. F was capable of "multi-threading", it could send multiple e-mails simultaneously, allowing it to dispatch thousands in minutes. Blaster worked by creating a "buffer overrun in the remote procedure call". In English, that means it attacked a piece of software used by Microsoft’s Windows operating system to allow one computer to control another. It did so by causing that software to use too much memory. Most worms work by exploiting weaknesses in an operating system, but whoever wrote Blaster had a particularly refined sense of humour, since the website under attack was the one from which users could obtain a program to fix the very weakness in Windows that the worm itself was exploiting. One way to deal with a wicked worm like Blaster is to design a fairy godmother worm that goes around repairing vulnerable machines automatically. In the case of Blaster some-one seems to have tried exactly that with a program called Welch. However. according to Mr, Haley, Welch has caused almost as many problems as Blaster itself, by overwhelming networks with "pings" --signals that checked for the presence of other computers. Though both of these programs fell short of the apparent objectives of their authors, they still caused damage. For instance, they forced the shutdown of a number of computer networks, including the one used by the New York Times newsroom, and the one organizing trains operated by CSX, a freight company on America’s east coast. Computer scientists expect that it is only a matter of time before a truly devastating virus is unleashed. SoBig. F damaged computer programs mainly by
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