"Usually when we walk through the rain forest we hear a soft sound from all the moist leaves and organic debris On the forest floor , " says ecologist Daniel Nepstad. "Now we increasingly get rustle and crunch. That's the sound of a dying forest. "
Predictions of the collapse of the tropical rain forests have been around for years. Yet until recently the worst forecasts were almost exclusively linked to direct human activity, such as clear-cutting and burning for pastures or farms. Left alone, it was assumed, the world's rain forests would not only flourish but might even rescue us from disaster by absorbing the excess carbon dioxide and other planet-warming greenhouse gases.Now it turns out that may be wishful thinking. Some scientists believe that the rise in carbon levels means that the Amazon and other rain forests in Asia and Africa may go from being assets in the battle against rising temperatures to liabilities. Amazon plants, for instance, hold more than 100 billion metric tons of carbon, equal to 15 years Of tailpipe and chimney emissions. If the collapse of the rain forests speeds up dramatically, it could eventually release 3 .5-5 billion metric tons Of carbon into the atmosphere each year—making forests the leading source Of greenhouse, gases.
Uncommonly severe droughts brought on by global climate changes have led to forest -eating wildfires from Australia to Indonesia , but nowhere more acutely than in the Amazon. Some experts say that the rain forest is already at the brink of collapse.
Extreme weather and reckless development are plotting against the rain forest in ways that scientists have never seen. Trees need more water as temperatures rise, but the prolonged droughts have robbed them of moisture, making whole forests easily cleared of trees and turned into farmland. The Nino picture worsens with each round of EI Nino,the unusually warm currents in the pacific Ocean that drive up temperatures and invariably presage droughts and fires in the rain forest. Runaway fires pour even more carbon into the air, which increases temperatures, starting the whole vicious cycle all over again.
More than paradise lost, a perishing rain forest could trigger a domino effect—sending winds and rains kilometers off course and loading the skies with even greater levels of greenhouse gases—that will felt far beyond the Amazon basin. In a sense, we are already getting a glimpse of what's to come. Each burning season in the Amazon, fires deliberately set by frontier settlers and developers hurl up almost half a billion metric tons of carbon a year, placing Brazil among the top five contributors to greenhouse gases in the world.
We learn from the first paragraph that ______
A.dead leaves and tree debris make the same soundWhen social scientists use the term culture they tend to be talking about a less restrictive concept than that implied in everyday speech. In social science,culture is all that in human society which is socially rather than biologically transmitted,whereas the commonsense usage tends to (26)______ only to the arts. Culture is thus a general term for the symbolic and learned aspects of human society,although some animal behaviourists now (27)______ that certain primates (灵长类动物)have at least the capacity for culture。
Social anthropological ideas of culture are based to a great(28)_____on the definition given by Edward Tylor in 1871,in which he referred to a learned complex of knowledge,belief,art,morals,law,and custom.This definition implies that culture and civilization are one and the same. But this equation, although possible in English and French usage,runs (29)_______ to the German distinction between Kultur and Zivilisation,the former referring to symbols and values, while the latter deals with the organization of society.Archaeological usage, though (30)______the wholeness of human societies,makes a distinction between material culture and practice sand beliefs,the non-material or adaptive culture transmitted by teaching and tradition. Only material culture is(31)______to archaeology,whereas adaptive culture is the subject of history,sociology, and anthropology.
For nineteenth century anthropologists,such as Tylor and Lewis HenryMorgan, culture was a conscious creation of human rationality.Civilization and culture, in this conception,showed a progressive tendency towards what were regarded as higher moral values, and this enabled the Victorian mind to construct a (32)______of cultures or civilizations which provided a rationale for colonial activities by apparently higher-order Western civilizations .
In America,it is sometimes argued that the concept of culture can provide ways of explaining and understanding human behaviour,belief systems,values, and(33)______,as well as particular culturally specific personality types.
In cultural anthropology,analysis of culture may proceed at three levels: learned patterns of behaviour; aspects of culture that act below conscious levels(such as the deep level of grammar and (34)______ in language,of which a native language speaker is seldom aware); and patterns of thought and (35)______,which are also culturally determined.
A.ideologies
B.perception
C.hierarchy
D.junk
E.grandeur
F.point
G.syntax
H.forfeit
I.extent
J.counter
K.dissipate
L.acknowledging
M.teeming
N.accessible
O.assert
"Depression" is more than a serious economic downturn. Khat distinguishes a depression from a harsh recession is paralyzing fear—fear of the unknown so great that it causes consumers, businesses, and investors to retreat and panic. They save up cash and desperately cut spending. They sell stocks and other assets . A shattering loss Of confidence inspires behavior that overwhelms the normal self-correcting mechanisms that usually present a recession from becoming deep and prolonged: a depression.
Comparing 1929 With 2007-09, Christina Romer, the head Of President Obama ' s Council Of Economic Advisers, finds the initial blow to confidence far greater now than then. True, stock prices fell a third from September to December 1929, but fewer Americans then owned stocks. Moreover, home prices barely dropped. From December 1928 to 1929, total household wealth declined only By contrast, the loss household wealth between December 2007 and December 2008 was 17%. Both stocks and homes, more widely held, dropped more. Thus traumatized(收到创伤) , the economy might have gone into a free fall ending in depression. Indeed, it did go into free fall. Shoppers refrained from buying cars, appliances, and other big-ticket items. Spending on such "durables" dropped at a annual rate in 2008's third quarter, a rate in the fourth. And businesses shelved investment projects.
That these huge declines didn't lead to depression mainly reflects, as Romer argues, countermeasures taken by the government. Private markets for goads, services, labor, and securities do mostly self-correct, but panic feeds on itself and disarms these stabilizing tendencies. In this situation, only government can protect the economy as a whole, because most individuals and companies are involved in the self-defeating behavior Of self-protection.
Government 's failure to perform this role in the early 1930s transformed recession into depression. Scholars Will debate Which interventions this time--the Federal Reserve's support Of a failing credit system, guarantees Of bank debt, Obama's "stimulus" plan and bank "stress test '—counted most in preventing a recurrence. Regardless, all these complex measures had the same psychological purpose; to reassure people that the free fall would stop and, thereby, curb the fear that would perpetuate(持久) a free fall.
All this improved confidence. But the consumer sentiment index remains weak, and all the rebound has occurred in Americans' evaluation of future economic conditions, not the present. Unemployment (9.8%) is abysmal (糟糕的) , the recovery's strength unclear. Here, too, there is an echo from the 1930s. Despite bottoming out in 1933, the Depression didn't end until World War II. Some government policies aided recovery; some hindered it. The good news today is that the bad news is not worse.
What is the chief purpose of all the countermeasures taken?
A.To create job opportunities free tall.
2. 画出锅炉炉水泵一次水系统图。
3. 画出电厂循环水泵冷却及润滑水系统图。
4. 画出两相三继电器式的不完全星形原理接线图。
答案:答:如图E-8所示。
图E-8
5. 画出双冲量汽温调节系统示意图,并注明设备名称。
答案:答:如图E-9所示。
图E-9
6. 画出单相电压互感器接线图。
答案:答:如图E-10所示。
图E-10
7. 画出三相电源与负载采用"三相四线制"连接的电路图。
答案:答:如图E-11所示。
图E-11
8. 画出三相两元件有功功率表接线图。
答案:答:如图E-12所示。
图E-12
9. 画出6kV工作段接线图。
10. 画出电厂给水泵密封水系统图。
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