occurrence

n.发生，事件，出现

obviousness, ocarina, occasion, occasional, occasional table, occasionally, Occident, Occidental, occlude, occult, occultist, occupancy, occupant, occupation, occupational, occupied, occupier, occupy, occur, occur to, ocean, ocean lane, ocean-going, oceanarium, Oceania, oceanic, oceanography, ocelot, ochre (US also ocher), Oct, oct(o)-, octagon, octagonal, octane, octane number (also `octane rating), octave, octavo, octet (also octette), October, octogenarian,