optimism

n.乐观

oppress, oppress-ively, oppressed, oppression, oppressive, oppressor, opprobrious, opprobriously, opprobrium, ops, opt, opt out of, optic, optical, optical art, optical illusion, optically, optician, optics, optimal, optimist, optimistic, optimistically, optimization, optimize, optimum, option, optional, optometrist, opulence, opulent, opus, or, or else, or rather, or so, oracle, oracular, oral, orally,