But other errors are less easily explained: between 1990 and 2007, the IMF's spring forecasts underestimated global growth in 13 of the 18 years,  但是其他一些错误却难以解释：1990年至2007年这18年之间，有13年国际货币基金组织的春季预测低估了全球增长，

　　in large part because it failed to foresee the spectacular rise of China. 很大一部分是因为它未能预见中国惊人的崛起。

　　Since the financial crisis, however, the IMF has had to revise down its forecasts over time every year since 2010. 然而自经济危机一来，从2010年起，国际货币基金组织不得不渐渐每年修改其预测。

　　The fund's spring forecasts for the coming year have turned out to be over-optimistic in the past three years. 在过去三年，该组织对来年经济的春季预测结果是过于乐观。

　　Christine Lagarde, the IMF's boss, recently conceded that economic growth in the past six years has been “disappointing”, but held firm in her belief that the world economy was turning. 国际货币基金组织的总裁克里斯蒂娜·拉加德最近承认过去六年经济增长一直“差强人意”，但是坚持她的信念，相信世界经济正在回转。

　　Hence the positive revision to its global GDP forecast—albeit by just a tenth of a percentage point. 因此，对全球GDP预测的乐观看法—尽管只有百分之十分之一。

　　The global economy may still falter for a number of reasons. 全球经济可能仍然会因为一些原因停止不前。

　　Ms Lagarde worries the rich world will suffer “self-inflicted wounds” from poor policy choices, notably on trade. 拉加德担心发达国家将从不合理的政策选择中遭受“自我伤害”，特别是在贸易方面。

　　Political uncertainty abounds. 政治不确定性比比皆是。

　　Just hours before the IMF released the WEO came the surprising news of an imminent election in Britain. 正在国际货币基金组织发布世界经济展望后几个小时，出现了英国出人意料选举的惊人消息。

　　The known unknowns hardly help, either. 已知的未知数也没有帮助。

　　Mr Trump's fiscal policies, for example, are far from firm plans—Maurice Obstfeld, the IMF's chief economist, calls them “a work in progress”. 例如，特朗普的财政政策根本不是稳定的计划--国际货币基金组织的首席经济学家莫里斯·奥布斯特菲尔德把这些政策称为“在发展中的工作”。