Title: Vacuum.
Question: When are electric and magnetic fields with zero average values, but their variances are not at zero?

Title: New Haven, Connecticut.
Question: The city of New Haven was often referenced several time by a character in a very popular novel which name was?

Title: British Empire.
Question: Which British territory received independence in 1962?

Title: 2008 Sichuan earthquake.
Question:
What are the estimations of how many schoolrooms collapsed?