9/11 explosive evidence, page-140

"WTC was designed to withstand a passenger jet hitting it but it did not, so the conclusion is that it was impossible?"

Weren't the twin towers built in the late 60's early 70's??? Is it not it not possible that with the advances in Jets, the towers became a little outdated in their structure?

Also, how many jets did the fly into buildings to know it was 100% fool proof prior to the 70s when it was built.

And, there are plenty of building which are built to withstand earthquakes, hurricanes, cyclones etc and some still manage to have severe structural damage or are basically written off.