Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

Example Input: Seymour is the family name of which English duke?
Example Output: duke

Example Input: Physics. What is the SI unit for amount of substance?
Example Output: amount of substance

Example Input: Who played Lionel Hardcastle in the TV series 'As Time Goes By'?
Example Output:
as time goes by