optimum

n.最适条件，最佳效果，最优化

opprobrious, opprobriously, opprobrium, ops, opt, opt out of, optic, optical, optical art, optical illusion, optically, optician, optics, optimal, optimism, optimist, optimistic, optimistically, optimization, optimize, option, optional, optometrist, opulence, opulent, opus, or, or else, or rather, or so, oracle, oracular, oral, orally, orang-utan, orange, orange squash, orange-blossom, orange-coloured, orangeade,