A．Different uses of com．
B．The history of the development of com．
C．The popularity of corn．
D．Increasing the production of corn．

A．Europe．
B．The Caribbean Islands
C．Canada．
D．Mexico．

A．It must be watered by people．
B．It has to be protected from stealing．
C．It has to be protected from natural disasters．
D．It will be eaten out by other animals．