RETURN TICKET TO CHINA

There is some thing i would like to understand about the Return ticket requirement when applying for a student's visa. look at a situation where i will stay at school for four years before the end of my course can my return ticket be scheduled for me to be on a flight after four years that i need to book it now or i can as well book a one way ticket to china and keep the money necessary for a return ticket near by, just in case an emergency that requires me to return arises