中文摘要：

实证研究表明，在需求约束型经济态势下，美国经济增长的动力是总需求，观察美国经济下一步走势的重要指标是代表总需求的货币流量，即M1和影响货币流通速度的价格预期因素。长期中，美国的进口主要受国民收入影响，弹性值平均在1．85左右。在1919～2008年的90年中，虽然有一定的经济周期性波动，但上述规律的总趋势不改。20世纪90年代以来，中国出口美国的商品额对美国总进口额的弹性在1．68左右。因此，从美国货币流量角度观察，短期内不能指望中国对美国的出口有较大增长。

英文摘要：

Empirical studies show that aggregate demand has been the engine of US economic growth under the demand-constrained economic system. The important indicator to observe the trend of US economy is money flow which represents aggregate demand, namely, M1 and expected-price which influences the velocity of money circulation. US imports are mainly affected by the national income, and the value of elasticity is around 1.85 at an average in the long run. Although there are some cyclical fluctuations, these laws do not change the general trend from 1919 to 2008. The elasticity of China＇s merchandise exports to the United States to the total imports of the United States is around 1.68. Therefore, the observation from US money flows indicates that China＇s exports to the United States are not expected to increase considerably in the short term.