[farming]
John studied agriculture because he wanted to be a farmer.
aid
[(1) to help; (2) to support; (3) help, assistance] He offered to aid the victims of the fire. (1)
Did you give money to aid the Democratic or the Republican candidate? (2)
Congress voted to provide aid to the flood victims. (3)
aim
[(1) to point a gun at; (2) a goal or purpose]
You cannot hit the target if you do not aim the gun. (1) The aim of the reformers is to improve government. (2)
air
[the mixture of gases around the earth, mostly nitrogen and oxygen, that we breathe]
The air is clean in the mountains.
air force