a. How big is world trade today in percentage of world GDP?

b.When did world trade begin to grow rapidly?

c.Why do you think world trade expanded at that time?

d.How does growth typically affect the shape of the production possibilities frontier (PPF)? You can either do that using words, or graphs or math. What is the effect on the terms of trade for a country on such growth? Can you give an example?

This is the course of international economic theory. I would really appreciate if you can give assistance for me.