opportunist

n (esp derog 尤作贬义) person who acts like this 机会主义者: There were many opportunists and few men of principle. 机会主义者多, 坚持原则的人绝无仅有.

operative, operator, operetta, ophthalmic, ophthalmic optician, ophthalmologist, ophthalmology, ophthalmoscope, opiate, opine, opinion, opinion poll, opinionated, opium, opossum, opp, opponent, opportune, opportunely, opportunism, opportunistic, opportunity, oppose, opposed, opposite, opposition, oppress, oppress-ively, oppressed, oppression, oppressive, oppressor, opprobrious, opprobriously, opprobrium, ops, opt, opt out of, optic, optical,