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若每一条指令都可以分解为取指、分析和执行三步。已知取指时间t 取指 =4△t，分析时间t 分析 =3△t，执行时间t执行=5△t。如果按串行方式执行完100条指令需要 6 △t。如果按照流水线方式执行，执行完100条指令需要 7 △t。 6处选择（）
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采用UML进行软件建模过程中， 1 是系统的一种静态视图，用 2 可明确表示两类事物之间存在的整体/部分形式的关联关系。 1处选择（）
Advances in computers and data networks inspire visions of a future "information economy" in which everyone will have (1)_____ to gigabytes of all kinds of information anywhere and anytime, (2)_____ information has always been a (3)_____ difficult commodity to deal with, and, in some ways, computers and high-speed networks make the problems of buying, (4)_____, and distributing information goods worse (5)_____ better. The evolution of the Internet itself (6)_____ serious problems. (7)_____ the Internet has been privatized, several companies are (8)_____ to provide the backbones that will carry traffic (9)_____ local networks, but (10)_____ business models for interconnection—who pays how much for each packet (11)_____, for example—have (12)_____ to be developed. (13)_____ interconnection standards are developed that make (14)_____ cheap and easy to transmit information across independent networks, competition will (15)_____. If technical or economic (16)_____ make interconnection difficult, (17)_____ transmitting data across multiple networks is expensive or too slow, the (18)_____ suppliers can offer a significant performance (19)_____; they may be able to use this edge to drive out competitors and (20)_____ the market.
Advances in computers and data networks inspire visions of a future "information economy" in which everyone will have (1)_____ to gigabytes of all kinds of information anywhere and anytime, (2)_____ information has always been a (3)_____ difficult commodity to deal with, and, in some ways, computers and high-speed networks make the problems of buying, (4)_____, and distributing information goods worse (5)_____ better. The evolution of the Internet itself (6)_____ serious problems. (7)_____ the Internet has been privatized, several companies are (8)_____ to provide the backbones that will carry traffic (9)_____ local networks, but (10)_____ business models for interconnection—who pays how much for each packet (11)_____, for example—have (12)_____ to be developed. (13)_____ interconnection standards are developed that make (14)_____ cheap and easy to transmit information across independent networks, competition will (15)_____. If technical or economic (16)_____ make interconnection difficult, (17)_____ transmitting data across multiple networks is expensive or too slow, the (18)_____ suppliers can offer a significant performance (19)_____; they may be able to use this edge to drive out competitors and (20)_____ the market.
The benefits of some environmentally friendly policies will not be apparent until decades after they have been enacted. (46)That is one of the messages of a report from the United Nations Environment Programme, which, even by the standards of global environment assessments, is sobering reading.(47)Global Environmental Outlook 3(GE03), a study of the links between environmental, social and development issues, contains a range of dreadful but familiar predictions about the impact of factors such as climate change and industrial development.But the report, released last week in the run-up to August"s World Summit on Sustainable Development in Johannesburg, was unusually pessimistic about the prospects for reversing the damage. The new predictions are contained in one of four possible futures outlined in the report. The authors considered situations in which global politics were dominated by concerns over markets, environmental and social policies, security, or sustainability. These were based on attempts to calculate the effect of the different approaches on population levels, economics, technology and governance. Some of the situations produced a familiar picture. (48)In a world dominated by a market mentality, for example, land and forest ruin becomes a critical issue, particularly in Latin America and the Caribbean.But the sustainability situation"s predictions shocked some of the authors. "The delays between changing human behavior and environmental recovery came as the biggest surprise to the regional experts", says Jan Bakkes of the National Institute of Public Health and the Environment in Bilthoven, the Netherlands, one of the report"s authors. (49)The report found that even if environmentally friendly approaches were adopted now, carbon dioxide concentrations would continue to rise until 2050.Water shortages would continue and coastal pollution would increase slightly. Bakkes blames difficulty in changing energy and transport infrastructures. Originally used during the 1950s to simulate future conflicts, situations were revived in an improved form by the Intergovernmental Panel on Climate Change (IPCC) in the early 1990s. "By adding situations to assessments you come up with a credible story about how the world might develop and can translate that into quantifiable formation". says Bert Metz, also at the Bilthoven institute and co-chair of the IPCC working group on strategies for tackling climate change. More than 1,000 scientists contributed to GEOs, which divides the world into no less than 17 different regions. (50)By contrast, the IPCC has used just four regions in previous assessments, although the panel"s new chair, energy economist Rajendra Pachauri, has pledged to improve regional detail in future studies.
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