大规模战争经常会阻碍国际贸易和金融活动的正常进行。在这种情况下，大部分汇率失去了彼此之间的关联性，一旦

战争结束，政府就会面临以什么比率重新确定汇率的问题。购买力平价理论经常被用于战后汇率重新安排的依据。现在假设你是英国财政大臣并假设第一次世界大战刚刚结束，请说明你将如何运用购买力平价理论来决定英镑对美元的汇率。在什么情况下，运用这一理论可能是不合适的？

Large-scale wars typically bring a suspension of international trading and financial activities．Exchange rates lose much of their relevance under these conditions，hut once the war is over governments wishing to fix exchange rates face the problem of deciding what the new rates should be．The PPP theory has often been applied to this problem of postwar exchange rate realignment．Imagine that you are a British Chancellor of the Exchequer and World War I has just ended．Explain how you would figure out the dollar/pound exchange rate implied by PPP．When might it be a bad idea to use the PPP theory in this way？