Change the sentence into passive voice.
They had built the new bridge before the river flooded the town.
Had the bridge been built by them before the river flooded the town?
Has the bridge been built by them before the river flooded the town?
Was the bridge being built by them before the river flooded the town?
Was the bridge been built by them before the river flooded the town?
Had the bridge being built by them before the river flooded the town?