【答案解析】A: Do you know there is the premier controversy in international trade= whether to follow a policy of free trade or selected protectionism. B: Yes, I've heard of that. In fact, there are two extreme conditions in national policy. At one extreme, a government could pursue a "laissez faire" policy with respect to trade and thus impose no regulation whatsoever that would impede the free voluntary exchange of goods between nations. We define this condition as free trade. A: Yes, at the other extreme, a government could impose such restrictive regulations on trade as to eliminate all incentive for international trade. We define this condition in which no international trade occurs as national autarky. Autarky represents a state of isolationism. Protectionism just locates in the middle. B: Probably, a pure state of free trade or autarky has never existed in the real world. All nations impose some form of Wade policies. And probably no government has ever had such complete control over economic activity as to eliminate cross-border Wade entirely.