Dishwasher and tunnelling shield: what they have in common

1. Step 1. Dishwasher — has part — Centrifugal pump. A pump feeds water to the spray arms.
2. Step 2. Centrifugal pump — is part of — Water tower. Filled by pumps.
3. Step 3. Water tower — is made of — Brick. Water towers are brick.
4. Step 4. Brick — is material for — Metro. The vaults of the first tunnels are brick.
5. Step 5. Metro — uses — Tunnelling shield. Metro tunnels were built with shields.

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