Resale and trade-in values for late-model vehicles in good condition have been rising all year as demand has outstripped supply, particularly for fuel-efficient models.
Using system engineering theory and method, system modeland simulation method, the paper analyses the conflict between supply and demand of water resources within the system.
文章用系统工程的理论和方法，用系统模型和模拟的方法，分析系统内水资源的供给与需求。
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The most important lesson we can learn from the supplyanddemandmodel is that with increased demand comes increased price competition.