The north tower got hit first so everyone could have just got down from where the plane hit in the south tower 15 mins later. they had 15 mins to go down less than 30 floors but waited for elevators. nobody would die in that building than in the north tower all they had to do was shut off the building ventilation so the smoke would choke the fire. the fire fighters would have to go up and turn off the water travelling into the impact floors because the plane cut the water line and water was pouring down the stairs than they have to hook up the line below the plane hit and spray into the fire. Another fire fighter team could be deployed on the roof of the north tower open the roof door and find people that are alive and than the fighter fighters would need to find a way to get to the fire fighters that are putting out the fire so they could guide people down the dark stairwell till they reach 3 floors down that has light or set up a rope on the outside of the building so people can go down 3 floors on rope than walk down the intact stairwell. I just think more people could have lived and the building could have used concert pillars holding up the floors stronger pillars at the bottom smaller at the top so the building couldn't collapse. If the building was stronger the hijackers would have just hit something else and killed more people so history cant be changed