driven in part by falling Venezuelan supply and the prospect of American sanctions on Iran. It now stands at around $82. 而出现这种现象部分是由于委内瑞拉石油供应量下降以及美国对伊朗实施制裁的前景。现在石油价格为82美元。

　　Costly fuel used to threaten the American economy. Today, however, it spurs investment in shale rigs. 过去高额的燃料会对美国经济造成威胁，而今却刺激了其对页岩油设备的投资。

　　That gives America a natural hedge against oil-price shocks, even though, in the short term, limited pipeline capacity might mean investment responds only slowly. 这给了美国一个避免石油价格冲击的天然避险策略，虽然短期来看，有限的管线输送能力或许意味着投资回报缓慢。

　　Finally, there is Mr Trump's trade war. America will eventually suffer from the distortive effects of rising tariffs, 最后，还有特朗普的贸易战争。美国最终将遭遇关税上涨的扭曲性影响，

　　but it is not all that dependent on trade to fuel demand in the short term. 但要在短期内刺激需求并不完全依赖于贸易。

　　Forecasts of the effect of existing tariffs on American growth and inflation predict only a small impact. 预计现有关税对美国经济增长和通货膨胀的影响并不大。

　　The result is that the trade war so far also looks like an asymmetric shock—certainly as far as China is concerned. 这是因为到目前为止，这场贸易战似乎是一种非对称性冲击—就中国而言是这样的。

　　The danger is that America's outperformance pushes the dollar even higher, leading to more volatility in global finance and crimping growth in emerging markets. 危险之处在于美国的优势推动美元增值，给全球金融造成更多的不定性，也给新兴市场的增长造成更多阻碍。

　　Yet America's boom will not last for ever. Tax cuts will no longer provide incremental stimulus after 2019. 但美国的繁荣不会一直持续下去。2019年后，减税政策将不再有增值刺激。

　　Some forecasters fret that an end to the largesse, together with higher interest rates, may be sufficient to tip the country into recession by 2020. 一些预测者担心截至2020年，慷慨救助的终止加上更高的利率，或许这足以让一个国家陷入经济衰退。

　　Analysts expect America's economy, with its ageing population, to expand by less than 2% a year in the long run. 分析家预测随着其老龄化加剧，美国经济的增长最终不会超过2%。

　　That suggests that, unless productivity surges, a slowdown must eventually come. 这表明，除非生产力暴增，否则经济下滑必将到来。

　　The question then is whether the rest of the world can withstand, let alone make up for, an eventual slowdown in America. 那么到那时其他国家是否能抵挡得住美国最终的经济下滑都是个问题，更别提要进行弥补了。

　　Not long ago, the consensus may have been that it could cope. Now there is more to worry about. 不久前，各方或许还一致认为其可以应对。现在有更多事情需要担心了。