20世纪70年代末 英国一夜暴富——由于早几年北海油田的成功开发 以及1970～1980年间石油价

20世纪70年代末，英国一夜暴富——由于早几年北海油田的成功开发，以及1970～1980年间石油价格的飞涨，英国国民收入突然迅速增加。然而到了80年代初期，由于世界性的经济滑坡和对石油需求的减少。油价下降。

  在下表中我们列出了英镑对一些外国货币的平均实际汇率指数(这些平均指数被称为实际有效汇率)。这些指数中任何一个数值的提高都意味着英镑的实际升值，即英国的价格水平相对于用英镑表示的外国平均价格水平提高，反之则为贬值。

  请用以上信息解释英国1978～1984年实际有效汇率变动的原因，请注意非贸易品的作用。

  In the late 1970s Britain seemed to have struck it rich．Having developed its North Sea oil-producing fields in earlier years，Britain suddenly found its real income higher as a result of a dramatic increase in world oil prices in 1979-1980． In the early 1980s，however，oil prices receded as the world economy slid into a deep recession and world oil demand faltered．

  On the following page，we show index numbers for the average real exchange rate of the pound against several foreign currencies．(Such average index numbers are called real effective exchange rates.)A rise in one of these numbers indicates a real appreciation of the pound，that is，an increase in Britain's price level relative to the average price level abroad measured in pounds．A fall is a real depreciation．

  Use the clues we have given about the British economy to explain the rise and fall of the pound's real effective exchange rate between 1978 and 1984． Pay particular attention to the role of nontradables．