Il libro Face2face - Intermedio Superiore - Unità 2 - 2A

the number of times an event recurs in a unit of time

used to refer to something that happens rarely or infrequently

on a very infrequent basis

in a way that occurs occasionally or infrequently

occasionally but repeatedly over time

In a way that occurs frequently or regularly, but not all the time

on irregular but not rare occasions