1 Trade as an engine of growth, Measurement of gains from trade, Free Trade Theory- Absolute advantage, comparative advantage & opportunity cost, Modern theories of international trade: Theorem of factor price equalization, H-O Theory, Kravis & Linder theory of trade. 2 Role of dynamic factors : tastes, technology & factor endowments in trade, I. B. Kravis has developed the availability theory against the comparative cost theory as a plausible explanation of international trade in certain cases. His argument is that country exports certain scarce resources in the world because these are available with it. For instance Gulf countries export oil, because oil fields are deposited with them.