出典:Wiktionary
An opportunity once lost is lost for ever.
Such an opportunity may not occur again.
having a few opportunities to visit (someone)
It was not long before an opportunity presented itself―an opportunity occurred―an opportunity offered.
till a good chance offers itself
I don't have that kind of opportunity.
Don't throw away your chance.
Principles often clash with interests.
Privilege often gives rise to abuses.
let an opportunity slip (by)