So stove burners have to be replaced every 30 years? Or every couple of years? How many years did the towers burn?

As far as Ebbie, CarolC, I've found her intransigence to be a good thing. For whatever reason, she refuses to publicly acknowledge the obvious.   And that's good. She is the howling wind that the shouted truth needs to overcome. I think she poses as a hardhead just to stimulate debate. She gives people a chance to state and restate the obvious fact that 19 men with boxcutters didn't go from Cessna classes to trick flying of passenger jets, get NORAD and the FAA to drop the ball over and over for an hour and a half, then get congress to cover up the whole affair with a whitewash.