题目内容
P148Lead-in[音频]Task 1. Listen to an adapted excerpt of Earth in the Balance by Al Gore. Which two factors have changed our relationship to the Earth in the 20th century according to the audio clip?
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Listen to a brief introduction to global warming and decide whether the following statements are true(T) or false (F).( )1.Carbon dioxide traps heat in the atmosphere.( )2.Greenhouse gases have no benefit for human beings.( )3.Burning natural gas will not create carbon dioxide.( )4.The concentration of carbon dioxide in the atmosphere has increased by 13% during the industrial age.[音频]
等成本线代表总成本相等时的不同的(K,L)组合。
要素价格不发生变化,增加或减少预算会使等成本线平行移动。
等成本曲线远离原点向外平行移动,表明生产要素的价格按相同比例提高了。
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