observe vt.遵守;看到;說;
obtain vt.獲得,得到,買到;
obvious a.明顯的,顯而易見的;
obviously ad.明顯地,顯然地;
occasion n.場合,時刻;時機;
occasional a.偶然的;臨時的;
occasionally ad.偶然;非經(jīng)常地;
occupation n.占領(lǐng),占據(jù);職業(yè);
occupy vt.占領(lǐng);占,占有;
occur vi.發(fā)生;出現(xiàn),存在;
occurrence n.發(fā)生,出現(xiàn);事件;
ocean n.海洋;洋;
Oceania n.大洋洲