Steel nib and laser: what they have in common

1. Step 1. Steel nib — evolved from — Quill pen. The metal nib replaced the quill.
2. Step 2. Quill pen — uses — Ink. It writes with ink.
3. Step 3. Ink — is used in — Printer. It prints with ink.
4. Step 4. Printer — includes — Laser printer. A printer.
5. Step 5. Laser printer — has part — Laser diode. A laser draws the image on the drum.
6. Step 6. Laser diode — is a kind of — Laser. A semiconductor laser.

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