When the right opportunity arises, I will take you to meet my mother.

He did finally return home, however, when an opportunity arose to do so.

They cannot help themselves if the opportunity for a good buy arises.

However, should the opportunity arise, I will call for you again.

"I would like to leave here this year if the opportunity arises."

Charles decided he must talk to her when the opportunity arose.

She might not even want to leave the ship when the opportunity arose to do so.

However, they "always left the door open so that if ever the opportunity arose and we could get some work together, then sure why not?"

If it doesn't happen this year, the opportunity may never arise again.

It may also be used for attack if an opportunity arises.