Input: Gregorian calendar
The Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days, but as in the Julian calendar, in a leap year, a leap day is added to February. In the Julian calendar a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years. In the Julian calendar, this leap day was inserted by doubling 24 February, and the Gregorian reform did not change the date of the leap day. In the modern period, it has become customary to number the days from the beginning of the month, and February 29th is often considered as the leap day. Some churches, notably the Roman Catholic Church, delay February festivals after the 23rd by one day in leap years.

On what day did both the Julian and Gregorian calendars add leap day?
Output: 24 February

Input: Clothing
According to archaeologists and anthropologists, the earliest clothing likely consisted of fur, leather, leaves, or grass that were draped, wrapped, or tied around the body. Knowledge of such clothing remains inferential, since clothing materials deteriorate quickly compared to stone, bone, shell and metal artifacts. Archeologists have identified very early sewing needles of bone and ivory from about 30,000 BC, found near Kostenki, Russia in 1988. Dyed flax fibers that could have been used in clothing have been found in a prehistoric cave in the Republic of Georgia that date back to 36,000 BP.

How was the earliest clothing kept on the body?
Output: tied around

Input: London
London's bus network is one of the largest in the world, running 24 hours a day, with about 8,500 buses, more than 700 bus routes and around 19,500 bus stops. In 2013, the network had more than 2 billion commuter trips per annum, more than the Underground. Around 850 million is taken in revenue each year. London has the largest wheelchair accessible network in the world and, from the 3rd quarter of 2007, became more accessible to hearing and visually impaired passengers as audio-visual announcements were introduced. The distinctive red double-decker buses are an internationally recognised trademark of London transport along with black cabs and the Tube.

What distinct appearance identifies many buses as a landmark for London?
Output: red double-decker

Input: Daylight saving time
In several countries, fire safety officials encourage citizens to use the two annual clock shifts as reminders to replace batteries in smoke and carbon monoxide detectors, particularly in autumn, just before the heating and candle season causes an increase in home fires. Similar twice-yearly tasks include reviewing and practicing fire escape and family disaster plans, inspecting vehicle lights, checking storage areas for hazardous materials, reprogramming thermostats, and seasonal vaccinations. Locations without DST can instead use the first days of spring and autumn as reminders.

In addition to smoke detectors, what do fire safety officials suggest people replace batteries in when they set their clocks twice a year?
Output:
carbon monoxide detectors