CH, H2C H2C、CH2 H3C CH CH HC 'CH or H,C CH H2C CH C、CH3CH2 H3C CH Many terpenes also have isoprene units linked in rings, and others(terpenoids) contain oxygenMany terpenes also have isoprene units linked in rings, and others(terpenoids) contain oxygen. H2C H2C CH CH2 CH C CH2 C H3C CH3 H2 C H2 C CH C H C H2 C C CH H2 C CH3 CH2 CH C H3 C CH3 CH3 or or