Title: High-definition television.
Question: In addition to the NTSC system, what 525-line system is considered a standard definition television system?

Title: Separation of church and state in the United States.
Question: What do critics of the concept of separation of church and state argue it's untethered to?

Title: Gothic architecture.
Question: In what century were distinct Gothic details used on new construction at Oxford and Cambridge?

Title: Incandescent light bulb.
Question:
What material were the first light bulb filaments made from?