Can anyone assist me with these questions?

 
Critical Thinking Questions:

Are differences in geography behind the

differences in absolute advantages?
2.  Why does the United States not have an absolute
advantage in coffee?
3.  Why might a low-income country put up barriers
to trade, such as tariffs on imports?
4.  Can a nation’s comparative advantage change over
time? What factors would make it change?
5.   What’s the difference between economic immigrants, legal immigrants, and illegal immigrants? Do immigrants help or hurt the economy. Explain.