一个半径比地球大2倍，质量是地球的36倍的行星，它表面的重力加速度是地球表面的重

诊断慢性支气管炎患者的标准是咳痰伴喘息每年发作（）

A.持续3个月、连续1年以上

B.持续3个月、连续2年以上

C.持续2个月、连续1年以上

D.持续2个月、连续2年以上

E.持续2个月、连续3年以上

二海丸功效与作用

约束反力的确定与约束类型及主动力有关，常见的约束有（）。

A.柔体约束

B.光滑接触面约束

C.圆柱铰链约束

D.链杆约束

E.固定端约束

If a heavy reliance on fossil fuels makes a country a climate ogre, then Denmark — with its thousands of wind turbines sprinkled on the coastlines and at sea — is living a happy fairy tale.
Viewed from the United States or Asia, Denmark is an environmental role model. The country is "what a global warming solution looks like," wrote Frances Beinecke, the president of the Natural Resources Defense Council, in a letter to the group last autumn. About one-fifth of the country’s electricity comes from wind, which wind experts say is the highest proportion of any country.
But a closer look shows that Denmark is a far cry from a clean-energy paradise. The building of wind turbines has virtually ground to a halt since subsidies were cut back. Meanwhile, compared with others in the European Union, Danes remain above-average emitters of the greenhouse gas carbon dioxide. For all its wind turbines, a large proportion of the rest of Denmark’s power is generated by plants that burn imported coal.
The Danish experience shows how difficult it can be for countries grown rich on fossil fuels to switch to renewable energy sources like wind power. Among the hurdles are fluctuating political priorities, the high cost of putting new turbines offshore, concern about public acceptance of large wind turbines and the volatility of the wind itself.
"Europe has really led the way," said Alex Klein, a senior analyst with Emerging Energy Research, a consulting firm with offices in Cambridge, Massachusetts.
Some parts of western Denmark derive 100 percent of their peak needs from wind if the breeze is up. Germany and Spain generate more power in absolute terms, but in those countries wind still accounts for a far smaller proportion of the electricity generated. The average for all 27 European Union countries is 3 percent.
But the Germans and the Spanish are catching up as Denmark slows down. Of the thousands of megawatts of wind power added last year around the world, only 8 megawatts were installed in Denmark.
If higher subsidies had been maintained, he said, Denmark could now be generating close to one-third — rather than one-fifth — of its electricity from windmills.