One of the most significant challenges is building an airplane had to do with "propulsion", since the technology that allowed motors to have enough energy to lift an airplane into the sky with a passenger wasn't available for most of history.
He is referring to the bombing of Britain by Hitler's forces (also known as the Nazis). He was also said to have stated about this "It is not the size of the dog in the fight; but the size of the fight in the dog."
When you put these questions up it would be smart to add the answer choices
