Read the passage below and answer the questions that follow:

Orville and Wilbur Wright, the inventors of the first flying machine, had always had a compelling interest in aeronautics and mechanics. As young boys, they earned money by making and selling kites and mechanical toys. Later, they built a printing press and operated a bicycle-repair shop. In 1903, the Wright brothers built their first airplane. They even designed and built their own source of propulsion - a lightweight gasoline engine. By 1905, they had perfected the first airplane that could remain airborne for half an hour at a time As the contributors of one of the most outstanding engineering achievements in history, the Wright brothers are called the fathers of aviation