The phrase 'could have confirmed' is correct and usable in written English.
It is used in the context of a missed opportunity, as in the example sentence: I could have confirmed the meeting dates earlier, but I forgot.
The branch could have confirmed her identity in another way.
Was eleven the right age for schizophrenia to set in? His wife, master of all matters psychological, could have confirmed this.
"The Labour party legally have access to the electoral register and could have confirmed the required information inside the seven days between my application and the rejection date".
What a child test rider could have confirmed in two seconds, the grown-ups reluctantly concluded after many minutes of discussion: the rocking horse didn't rock right.
The images don't reveal too much by themselves, but they could have confirmed a few stories about the long-awaited phone.
Johnson told the Press Association: "It was a demonstration of the essential spontaneity of the event and nothing could have confirmed more vividly that the space on top of the fourth plinth is open to the people".
He argued that it minimized the total number of judges who might have been confirmed before the midterm elections because McConnell could have kept senators in town and teed up votes on even more nominees than the agreed-on 15. "If we had stayed in session, McConnell could've confirmed more than the deal yielded," said this aide.
We could not have confirmed this assertion because we had been using the same procedure, the same equipment, and the same staff.
Labour says the heads of training establishments have confirmed they could set up the extra nurse places.
It's possible that Summers could have been confirmed without the support of this group, but it would have been a heck of a fight, and the White House would have been dependent on the support of Republicans.
