occur

vi.出现，发生；想到

obvious, obviously, obviousness, ocarina, occasion, occasional, occasional table, occasionally, Occident, Occidental, occlude, occult, occultist, occupancy, occupant, occupation, occupational, occupied, occupier, occupy, occur to, occurrence, 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),