Rolling mill and oil well: what they have in common

1. Step 1. Rolling mill — is part of — Steel works. Rolling mills.
2. Step 2. Steel works — has part — Overhead crane. Overhead cranes.
3. Step 3. Overhead crane — has part — Block and tackle. A block and tackle.
4. Step 4. Block and tackle — is part of — Drilling rig. The block and tackle lifts the drill string.
5. Step 5. Drilling rig — is used in — Oil well. A well is drilled by a rig.

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