Input: Read this: The most accurate timekeeping devices are atomic clocks, which are accurate to seconds in many millions of years, and are used to calibrate other clocks and timekeeping instruments. Atomic clocks use the frequency of electronic transitions in certain atoms to measure the second. One of the most common atoms used is caesium, most modern atomic clocks probe caesium with microwaves to determine the frequency of these electron vibrations. Since 1967, the International System of Measurements bases its unit of time, the second, on the properties of caesium atoms. SI defines the second as 9,192,631,770 cycles of the radiation that corresponds to the transition between two electron spin energy levels of the ground state of the 133Cs atom.
Question: Which system bases its unit of time on the properties of vibrations?

Output: unanswerable

Input: Read this: The 548 ft (167 m) City Hall remained the tallest building in the city until 1987 when One Liberty Place was constructed. Numerous glass and granite skyscrapers were built in Philadelphia's Center City from the late 1980s onwards. In 2007, the Comcast Center surpassed One Liberty Place to become the city's tallest building. The Comcast Innovation and Technology Center is under construction in Center City and is planned to reach a height of 1,121 feet (342 meters); upon completion, the tower is expected to be the tallest skyscraper in the United States outside of New York City and Chicago.
Question: How tall is the City Hall?

Output: 548 ft

Input: Read this: In 2010, there were 1.2 million people living in the greater Palermo area, 655,875 of which resided in the City boundaries, of whom 47.4% were male and 52.6% were female. People under age 15 totalled 15.6% compared to pensioners who composed 17.2% of the population. This compares with the Italian average of 14.1% people under 15 years and 20.2% pensioners. The average age of a Palermo resident is 40.4 compared to the Italian average of 42.8. In the ten years between 2001 and 2010, the population of Palermo declined by 4.5%, while the population of Italy, as a whole, grew by 6.0%. The reason for Palermo's decline is a population flight to the suburbs, and to Northern Italy. The current birth rate of Palermo is 10.2 births per 1,000 inhabitants compared to the Italian average of 9.3 births.
Question: Why has Palermo's population declined from 2001 to 2010?

Output: population flight to the suburbs

Input: Read this: The death penalty is sought and applied more often in some jurisdictions, not only between states but within states. A 2004 Cornell University study showed that while 2.5 percent of murderers convicted nationwide were sentenced to the death penalty, in Nevada 6 percent were given the death penalty. Texas gave 2 percent of murderers a death sentence, less than the national average. Texas, however, executed 40 percent of those sentenced, which was about four times higher than the national average. California had executed only 1 percent of those sentenced.
Question: What percentage of murderers in California are given the death penalty and subsequently freed?

Output:
unanswerable