They are always around, like the common cold, waiting for an opportunity.

Sometimes you'd wait a year or two for such an opportunity.

His mind once made up, he had not to wait long for an opportunity.

He'd been waiting for an opportunity to act, and he finally saw it.

She was waiting for an opportunity to speak to him.

He was waiting for his opportunity to spring into action.

"It was just waiting for an opportunity to be done right."

"I've been waiting for an opportunity to speak to you in private."

At first, he had thought she was waiting for an opportunity to finish her off.

My personal opinion is that they were just waiting for an opportunity.