Railway switch and liquid-propellant rocket engine: what they have in common

1. Step 1. Railway switch — is part of — Railway track. Switches.
2. Step 2. Railway track — is used in — Wright Flyer. The Flyer had no wheels: it took off along a wooden rail.
3. Step 3. Wright Flyer — is a kind of — Biplane. The Flyer is a biplane.
4. Step 4. Biplane — has part — Wing. Two tiers of wings.
5. Step 5. Wing — is part of — Space Shuttle. It landed like a glider.
6. Step 6. Space Shuttle — has part — Liquid-propellant rocket engine. Hydrogen-fuelled main engines.

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