改进题：Nations will usually produce and export those goods in which they have the greatest comparative advantage, and import those items in which they have the least comparative advantage.

译文：各国通常都生产和出口那些他们最具比较优势的产品，而进口那些他们最不具比较的产品。

改进题：Nations will usually produce and export those goods in which they have the greatest comparative advantage, and import those items in which they have the least comparative advantage.

译文：各国通常都生产和出口那些他们最具比较优势的产品，而进口那些他们最不具比较的产品。

改进的译文：各国通常都生产和出口那些他们最具比较优势的产品，而进口那些他们最不具比较优势的产品。