Tunnel lining and programmable logic controller: what they have in common

1. Step 1. Tunnel lining — is part of — Tunnel. A lining of concrete or segments.
2. Step 2. Tunnel — is used in — Metro. Tunnels.
3. Step 3. Metro — is made of — Brick. The vaults of the first tunnels are brick.
4. Step 4. Brick — is material for — Chemical plant. The furnaces and towers are brick.
5. Step 5. Chemical plant — has part — Programmable logic controller. Process control automation.

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