Answer:
Key Idea 1. Wilbur and Orville confirm the existence of tangential force.
Key Idea 2. Wind resistance is a concern that needs to be solved.
Key Idea 3. Wilbur estimates they will need at least an engine weighing one hundred pounds.
Key Idea 4. He estimates the first flying machine will only each low speeds.
Key Idea 5. Travel by land and water were solved in the nineteenth century.
Key Idea 6. The twentieth century will solve the problem of flight.
Explanation:
These are the correct answers. I know it's late, but it's for anyone else who may need them.