DNA双螺旋结构的叙述不正确的是( )A．戊糖磷酸位于螺旋外侧，碱基位于内侧 B．

因某种原因，甲、乙两人现面临A、B两种方案的选择，如果两人都选择A方案，则甲得到5个单位利益，而乙得到2个单位利益；如果甲选择A方案，乙选择B方案，则甲、乙均得到4个单位利益；如果甲选择B方案，乙选择A方案，则甲得到6个单位利益，乙得到1个单位利益；如果甲、乙均选择B方案，则各得到3个单位利益。假定甲、乙两人都按照自己利益最大化标准来进行算计和行动，都明白上述的利益得失情况，两人的选择不分先后。
据此，可推出( )。

A．甲选择B方案，乙选择B方案
B．甲选择A方案，乙选择B方案
C．甲选择A方案，乙选择A方案
D．甲选择B方案，乙选择A方案

这是一枝普通的小草，当人们对它讲 (164) 或唱歌，小叶片会左右舞动，宛如小草听到你的声 (165) 翩翩起舞，因而人们称它为舞草。舞草产于华南部分省区。当今许多植物 (166) 都种植有舞草，作为会动的宠物，备受 (167) 注。

Global warming may or may not be the great environmental crisis of the 21st century, but — regardless of whether it is or isn’t — we won’t do much about it. We will argue over it and may even, as a nation, make some fairly solemn-sounding commitments(承诺) to avoid it. But the more dramatic and meaningful these commitments seem, the less likely they are to be observed.

Al Gore calls global warming an “inconvenient truth,” as if merely recognizing it could put us a path to a solution. But the real truth is that we don’t know enough to relieve global warming, and — without major technological breakthroughs — we can’t do much about it.

From 2003 to 2050, the world’s population is projected to grow from 6.4 billion to 9.1 billion, a 42% increase. If energy use per person and technology remain the same, total energy use and greenhouse gas emissions(排放) (mainly, CO2) will be 42% higher in 2050. But that’s too low, because societies that grow richer use more energy. We need economic growth unless we condemn the world’s poor to their present poverty and freeze everyone else’s living standards. With modest growth, energy use and greenhouse emissions more than double by 2050.

No government will adopt rigid restrictions on economic growth and personal freedom (limits on electricity usage, driving and travel) that might cut back global warming. Still, politicians want to show they’re “doing something.” Consider the Kyoto Protocol(京都议定书). It allowed countries that joined to punish those that didn’t. But it hasn’t reduced CO2 emissions (up about 25% since 1990), and many signatories(签字国) didn’t adopt tough enough policies to hit their 2008-2012 targets.

The practical conclusion is that if global warming is a potential disaster, the only solution is new technology. Only an aggressive research and development program might find ways of breaking our dependence on fossil fuels or dealing with it.

The trouble with the global warming debate is that it has become a moral problem when it’s really an engineering one. The inconvenient truth is that if we don’t solve the engineering problem, we’re helpless.

46. What is said about global warming in the first paragraph?

A. It may not prove an environmental crisis at all.

B. It is an issue requiring worldwide commitments.

C. Serious steps have been taken to avoid or stop it.

D. Very little will be done to bring it under control.

47. According to the author’s understanding, what is Al Gore’s view on global warming?

A. It is a reality both people and politicians are unaware of.

B. It is a phenomenon that causes us many inconveniences.

C. It is a problem that can be solved once it is recognized.

D. It is an area we actually have little knowledge about.

48. Greenhouse emissions will more than double by 2050 because of ________.

A. economic growth                       

B. wasteful use of energy

C. the widening gap between the rich and poor  

D. the rapid advances of science and technology

49. The author believes that, since the signing of the Kyoto Protocol, ________.

A. politicians have started to do something to better the situation

B. few nations have adopted real tough measures to limit energy use

C. reductions in energy consumption (消耗) have greatly cut back global warming

D. international cooperation has contributed to solving environmental problems

50. What is the message the author intends to convey?

A. Global warming is more of a moral issue than a practical one.

B. The ultimate solution to global warming lies in new technology.

C. The debate over global warming will lead to technological breakthroughs.

D. People have to give up certain material comforts to stop global warming.

断路器的绝缘试验包括有测量绝缘电阻、测量介质损失角正切值、测量泄漏电流、交流耐压试验等。

一3岁犬，腿部受伤后出现感染，触诊患部有气性捻发音，从创口流出红褐色液体，该犬所患疾病最可能是（）。

A、厌气性坏疽

B、恶性水肿

C、蜂窝织炎

D、厌气性败血症

E、脓肿