Title: Gregorian calendar.
Question: How many days must be skipped to align the calendar with mean solar days in a year?

Title: Modern history.
Question: When did modern physics arise?

Title: Cyprus.
Question: Where did British writer Lawrence Durrell reside from 1952-1956?

Title: Race (human categorization).
Question:
Neil Risch found a 99.9% agree between genetic structure and people's description of their what?