Outboard motor and refrigerator: what they have in common

1. Step 1. Outboard motor — has part — Propeller. A propeller.
2. Step 2. Propeller — is part of — Electric fan. The blades.
3. Step 3. Electric fan — is part of — Convection oven. A fan circulates the air.
4. Step 4. Convection oven — has part — Thermostat. A thermostat.
5. Step 5. Thermostat — is part of — Refrigerator. A thermostat.

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