Complete the sentence by regretting an action we had every opportunity to take but failed to take, not a lack of opportunity or ability: The downpour damaged our equipment last Sunday. I wish we ___ waterproof covers beforehand. (order)

Explication

Had ordered marks regret about an available action that we failed to take before last Sunday's completed event. Could have ordered is a standard alternative when the regret concerns an unrealised or unavailable past opportunity, but that modal reading conflicts with the stated full opportunity here.