Which line from "On Becoming an Inventor" supports the idea that Dean's time at Worcester Polytechnic Institute was very useful to him even if he did not graduate?

I was intimidated by the huge buildings devoted to these studies, the knowledge I needed and wanted to gain.
I found that at college I could get help from my teachers with solving business problems and in learning new techniques for designing new things.
The professors gave me as much time as they reasonably could.
Every once in a while one would say, “Sorry, I've got to go teach a class.”