Zvinhu zvinoshandiswa zvinokosha zvinoshandiswa mukuongorora kunaka kwemvura. Vanoita basa rinokosha mukunzvera mwero wokushatisa wemiviri yemvura, iro rinokosha nokuda kwedziviriro yemhoteredzo nokuteerera mipimo yokudzora. COD mwero wechiverengero chose chose cheoksijeni chinodikanwa kuti uhwise mamemikoro echinhu chisina kufanira mumvura. Mwero yeCOD yakakwirira kazhinji kazhinji i