operation

n.运转；操作；手术；运算；作用

open-mouthed, open-plan, open-work, opencast, opener, opening, opening night, opening-time, openly, openness, opera, opera-glasses, opera-house, operable, operate, operatic, operatically, operating system, operating-table, operating-theatre, operational, operations room, operative, operator, operetta, ophthalmic, ophthalmic optician, ophthalmologist, ophthalmology, ophthalmoscope, opiate, opine, opinion, opinion poll, opinionated, opium, opossum, opp, opponent, opportune,