活动义齿修复需缓冲的区域是A．上颌硬区 B．下颌隆突 C．腭皱 D．下颌舌骨嵴 E．

下列属于合成高分子材料的囊材是( )。

A．阿拉伯胶
B．明胶
C．聚维酮
D．羧甲基纤维素
E．聚乳酸

如图所示，水平面C点以左是光滑的，C点以右是粗糙的，A、B两物体之间用轻质弹簧连接，用水平恒力F拉A，使A、B一起沿光滑水平面做匀加速运动，这时弹簧长度为；接着它们先后过C点进入表面粗糙的水平面后，A、B还是一起做匀加速运动，此时弹簧长度为。若A、B与粗糙水平面之间的动摩擦因数相同，则下列关系式正确的是

A．

B．

C．

D．以上都有可能

油环从缸壁上刮掉的润滑油（）

A.留在环槽内进一步润滑

B.从一个油道流回油底壳

C.通过环槽上的小孔返回油底壳

D.返回气缸盖

患者，男，54岁，咳血丝痰1个月余，吸烟20余年，体检左侧呼吸音减弱，外院X线平片提示左肺门浓密影。

进一步的影像学检查方法为

A．SPECT

B．超声

C．CT

D．MRI

E．PET

Remember global warming Back in December, the threat of climate change was thundering, and the rich countries agreed to cut their carbon-dioxide and other green-house-related emissions. Since then, interest has cooled markedly, and many European countries are already running away from the promises they made so loudly a few months ago. But there has been much talk, and a bit of action, to encourage renewable (可更新的) energies such as wind, hydro, solar and all living organisms. These emit no greenhouse gases, but tend to cost more than coal, oil or gas.

The better, simpler idea is to remember that the easiest way to reduce something is to tax it—in this case, by taxing the carbon content of power. The dirtier the power, the more tax it would pay. So dirty coal would be more expensive than clean coal, which would see its price rise in relation to oil, which would be even more expensive compared to gas, which would lose some of its price advantage over renewables.

Unless a carbon tax was so huge as to be economically crippling, it would not remove the price differential (差别) between all renewables and fossil fuels. But it would narrow that gap, by fixing the differing environmental costs into the price—a useful principle in itself. It would also give renewable producers a p incentive to cut costs, and fossil-fuel suppliers an motivation to clean their products.

Precedents suggest ply that a carbon tax would be effective. But the disadvantage to carbon taxes is political. After almost a decade of trying, the European Union gave up an attempt at a European carbon tax last year. Germany’s ruling coalition is fighting against a proposed energy tax. In America, politicians believe that even mentioning the notion is certain death. But many of the political objections could be met if a carbon tax were made up for the loss elsewhere, for example by lowering payroll or sales taxes. There is always suspicion when governments come up with clever new ways to tax, and rightly so. The response to that suspicion should be to win the argument, not to abandon it.

The standard of paying tax was ().

A. that the more carbon content of power it contained, the higher tax one would pay

B. that oil would be more expensive than clean coal

C. that renewables would be most expensive of all

D. in the order that renewables are the most expensive while clean coal the cheapest