Rectifier and r-7 rocket: what they have in common

1. Step 1. Rectifier — is part of — LED lamp. The driver in the base rectifies mains current and limits the LED current; in an ordinary bulb it has no transformer.
2. Step 2. LED lamp — evolved from — Incandescent light bulb. It replaced incandescent bulbs.
3. Step 3. Incandescent light bulb — evolved from — Oil lamp. The electric lamp replaced oil and gas lamps.
4. Step 4. Oil lamp — evolved into — Kerosene lamp. A development of the oil lamp.
5. Step 5. Kerosene lamp — uses — Kerosene. The fuel.
6. Step 6. Kerosene — is material for — R-7 rocket. The fuel is kerosene.

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