A、to lEArn how to prEvEnt A BonE DisEAsE.
B．to unDErstAnD DiFFErEnCEs BEtwEEn BonE tissuE AnD othEr tissuE.
C．to FinD out how spECiAlizED BonE CElls hAvE EvolvE
D、
D、to CrEAtE ArtiFiCiAl BonE tissuE.