行为发生不但与价值和实现的可能性有关，而且与实现的时间有关，说的是行为的
A. 强化模式
B. 时间价值期望模式
C. 健康意识模式
D. 个人控制力模式
With which of the Ten Principles of Economics is the study of international trade most closely connected? ( )
A. People face tradeoffs.
B. Trade can make everyone better off.
C. Governments can sometimes improve market outcomes.
D. Prices rise when the government prints too much money.
What is the fundamental basis for trade among nations? ( )
A. shortages or surpluses in nations that do not trade
B. misguided economic policies
C. absolute advantage
D. comparative advantage
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