Question: In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking motor that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided controls systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond VA, the electric elevator and control system in 1892, and the electric subway with independently powered centrally controlled cars, which were first installed in 1892 in Chicago by the South Side Elevated Railway where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry, while almost simultaneously another great inventor was developing its primary competitor, which would become much more widespread. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of a relatively small air gap between rotor and stator. Efficient designs have a comparatively small air gap. [a] The St. Louis motor, long used in classrooms to illustrate motor principles, is extremely inefficient for the same reason, as well as appearing nothing like a modern motor.
Is there an answer to this question: What was the transportation advancement made possible by Sprague's designs?

Answer: electric trolley system


Question: Roman histories and biographies anticipated the extensive mediaeval literature of lives of saints and miraculous chronicles, but the most characteristic form of the Middle Ages was the romance, an adventurous and sometimes magical narrative with strong popular appeal. Controversial, religious, political and instructional literature proliferated during the Renaissance as a result of the invention of printing, while the mediaeval romance developed into a more character-based and psychological form of narrative, the novel, of which early and important examples are the Chinese Monkey and the German Faust books.
Is there an answer to this question: Modern romance developed into what type of narrative?

Answer: unanswerable


Question: The Sultanate of Ifat, led by the Walashma dynasty with its capital at Zeila, ruled over parts of what is now eastern Ethiopia, Djibouti, and northern Somalia. The historian al-Umari records that Ifat was situated near the Red Sea coast, and states its size as 15 days travel by 20 days travel. Its army numbered 15,000 horsemen and 20,000 foot soldiers. Al-Umari also credits Ifat with seven "mother cities": Belqulzar, Kuljura, Shimi, Shewa, Adal, Jamme and Laboo.
Is there an answer to this question: Near what body of water did al-Umari say Ifat was located?

Answer: the Red Sea


Question: Antarctica is the coldest of Earth's continents. The coldest natural temperature ever recorded on Earth was −89.2 °C (−128.6 °F) at the Soviet (now Russian) Vostok Station in Antarctica on 21 July 1983. For comparison, this is 10.7 °C (20 °F) colder than subliming dry ice at one atmosphere of partial pressure, but since CO2 only makes up 0.039% of air, temperatures of less than −150 °C (−238 °F) would be needed to produce dry ice snow in Antarctica. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 cm (4 in) per year, on average. Temperatures reach a minimum of between −80 °C (−112 °F) and −89.2 °C (−128.6 °F) in the interior in winter and reach a maximum of between 5 °C (41 °F) and 15 °C (59 °F) near the coast in summer. Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it. Given the latitude, long periods of constant darkness or constant sunlight create climates unfamiliar to human beings in much of the rest of the world.
Is there an answer to this question: What was the coldest temperature ever recorded?

Answer:
−89.2 °C