International economic models are used to explain why nations trade and predict patterns.

a.What is the rationale (logic) used in the Standard Model to explain trade flows?

b.What are the terms of trade, what factors impact the terms of trade, and why are terms of trade important in international trade?

c.What characterizes the concept of external economies of trade?

This is a course of international economic theory I would really appreciate it you can give assistance to me.