Q. Some years ago, a professor of the electrical engineering...
Why is the word 'the' wrong here?
A. Using the definite article is wrong because because you are not referring to something specific. You would use "the" if you were saying "a professor in the electrical engineering department".
Q. It came floating down the aisle, gliding from out the cockpit...
why is the word 'from' wrong here?
A. "out of" and "from" cover the same idea of motion.
Q. Can be the word 'several' followed by the prepotition 'of'?
A. Yes. "Several of the people who are present", for example.
Q. Can be the word 'while' followed by the word 'during'? for instance:
-'electrical workers have also witnessed strange glowing balls while during their work'
A. "While" and "during" cover the same idea of something happening in a period of time. So you could say "while they were working" or "during their work".
Hope this makes some sense. Edmund