You may bring global temperatures back to pre-industrial levels, but the risk is that the poles will still be warmer than they should be and the tropics will be cooler than before industrialisation.

全球气温可能会回到工业化前的水平，但风险是两极的温度仍将高于正常水平，而热带地区的温度将比工业化前的要低。

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So here are a few higher-level takeaways, behind the fact that the growing legion Mac fanatics will be waiting to buy (or already are pre-ordering) their thinner, lighter, cooler iPad 2s on March 11.

越来越多的苹果迷正翘首以盼，等着到3月11日购买（或者已经开始预订）更薄、更轻、更酷的iPad2。 以下是由这一事实引发的几点深入思考。

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The indirect combined cycle, which consists of a steam cycle and a nitrogen gas turbine cycle with a pre-cooler, could be the first choice.

由蒸汽循环和带有预冷器的氮气透平循环构成的间接联合循环可以作为首选方案。

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The pre-cooler, also known as the heat exchanger, is made up of a huge number of tubes that use compressed helium to cool the air around it.

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The manufacturing process for the pre-cooler technology is already proven, but investors will be looking to see that the module has a stable operation and can meet the promised performance.

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The helium, which by then will have risen to about minus 15C, is pushed through a liquid nitrogen "boiler" to bring it back down to its run temperature, before looping back into the pre-cooler.

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