accident
accidents will happen

actually
did it actually happen?

anything
anything might happen

bind
this is bound to happen

cue
to happen on cue

happen
I happened to meet him

happen on
encontrar por acaso

happen upon
encontrar por acaso

liable
it's liable to happen

likely
this is likely to happen

possibility
it cannot happen by any possibility

schedule
to happen ahead of schedule

sense
...going to happen

telling
there is no telling what may happen

when
...things could happen is gone