opponent

n.对手，敌手；反对者

operating-theatre, operation, operational, operations room, operative, operator, operetta, ophthalmic, ophthalmic optician, ophthalmologist, ophthalmology, ophthalmoscope, opiate, opine, opinion, opinion poll, opinionated, opium, opossum, opp, opportune, opportunely, opportunism, opportunist, opportunistic, opportunity, oppose, opposed, opposite, opposition, oppress, oppress-ively, oppressed, oppression, oppressive, oppressor, opprobrious, opprobriously, opprobrium, ops,