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 188788 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 name of Chicago's first electric trolley system?

Answer: South Side Elevated Railway

Question: The war had removed Bermuda's primary trading partners, the American colonies, from the empire, and dealt a harsh blow to Bermuda's merchant shipping trade. This also suffered due to the deforestation of Bermuda, as well as the advent of metal ships and steam propulsion, for which it did not have raw materials. During the course of the following War of 1812, the primary market for Bermuda's salt disappeared as the Americans developed their own sources. Control of the Turks had passed to the Bahamas in 1819.
Is there an answer to this question: Who was Bermuda's main trading partner before the war?

Answer: American colonies

Question: The second major event of the early reign of Abd al-Malik was the construction of the Dome of the Rock in Jerusalem. Although the chronology remains somewhat uncertain, the building seems to have been completed in 692, which means that it was under construction during the conflict with Ibn al-Zubayr. This had led some historians, both medieval and modern, to suggest that the Dome of the Rock was built as a destination for pilgrimage to rival the Kaaba, which was under the control of Ibn al-Zubayr.
Is there an answer to this question: What year was the Kaaba completed?

Answer: unanswerable

Question: From the early 16th century, both Western Armenia and Eastern Armenia fell under Iranian Safavid rule. Owing to the century long Turco-Iranian geo-political rivalry that would last in Western Asia, significant parts of the region were frequently fought over between the two rivalling empires. From the mid 16th century with the Peace of Amasya, and decisively from the first half of the 17th century with the Treaty of Zuhab until the first half of the 19th century, Eastern Armenia was ruled by the successive Iranian Safavid, Afsharid and Qajar empires, while Western Armenia remained under Ottoman rule. In the late 1820s, the parts of historic Armenia under Iranian control centering on Yerevan and Lake Sevan (all of Eastern Armenia) were incorporated into the Russian Empire following Iran's forced ceding of the territories after its loss in the Russo-Persian War (1826-1828) and the outcoming Treaty of Turkmenchay. Western Armenia however, remained in Ottoman hands.
Is there an answer to this question: What came under Russian rule in the early 16th century?

Answer:
unanswerable