S. government Wangxia Treaty laid the strong foundation for American economic expansion to Far East, and from then on, the United States had the definitepolicy of China.
条约的签订为美国在远东地区推行经济扩张政策提供了重要基础，也是美国首次有了明确的对华政策。
2
A policy is a definite course or method of action selected from alternatives, and in light of given conditions, to guide and determine decisions.
策略是确定的路线或从选择物中选择动作的方法，并在给定条件的指引下指导及确定决策。
3
This article studies the optimal policy of production-inventory model in which time cycling is limited and cost parameter varies in stepped variation, and the definite way of cost parameter.