Calendário de parede e optical telegraph: o que têm em comum

1. Passo 1. Calendário de parede — é feito de — Paper. Calendars were printed on paper.
2. Passo 2. Paper — é material para — Outdoor. The poster is paper.
3. Passo 3. Outdoor — tem como parte — LED. LED screens.
4. Passo 4. LED — faz parte de — Traffic light. LEDs.
5. Passo 5. Traffic light — evoluiu de — Railway semaphore. The first traffic light was a railway-style semaphore.
6. Passo 6. Railway semaphore — evoluiu de — Optical telegraph. The semaphore idea.

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