What are the two factors that lead to tropical trees cooling down the land

A．They will find out what its people like.
B．They will argue in favor of this country and the language.
C．They will know the country and its people better.
D．They will like its inhabitants and their language.

A．They both require talent to study.
B．They are both expensive to study.
C．Arts can be appreciated through computers.
D．Computers can be designed with the help of arts.