Problem: Mandolin:

Beginning with the Paris Exposition of 1878, the instrument's popularity rebounded. The Exposition was one of many stops for a popular new performing group the Estudiantes Espanoles (Spanish Students). They danced and played guitars, violins and the bandurria, which became confused with the mandolin. Along with the energy and awareness created by the day's hit sensation, a wave of Italian mandolinists travelled Europe in the 1880s and 1890s and in the United States by the mid-1880s, playing and teaching their instrument. The instrument's popularity continued to increase during the 1890s and mandolin popularity was at its height in "early years of the 20th century." Thousands were taking up the instrument as a pastime, and it became an instrument of society, taken up by young men and women. Mandolin orchestras were formed worldwide, incorporating not only the mandolin family of instruments, but also guitars, double basses and zithers.

When was it said that mandolin's popularity peaked?
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A: early years of the 20th century.

Problem: Electric motor:

These motors were originally invented to drive the capstan(s) of magnetic tape drives in the burgeoning computer industry, where minimal time to reach operating speed and minimal stopping distance were critical. Pancake motors are still widely used in high-performance servo-controlled systems, robotic systems, industrial automation and medical devices. Due to the variety of constructions now available, the technology is used in applications from high temperature military to low cost pump and basic servos.

What are advantages of pancake motors?
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A: minimal time to reach operating speed and minimal stopping distance

Problem: Canon law:

The Greek-speaking Orthodox have collected canons and commentaries upon them in a work known as the Pedalion (Greek: , "Rudder"), so named because it is meant to "steer" the Church. The Orthodox Christian tradition in general treats its canons more as guidelines than as laws, the bishops adjusting them to cultural and other local circumstances. Some Orthodox canon scholars point out that, had the Ecumenical Councils (which deliberated in Greek) meant for the canons to be used as laws, they would have called them nomoi/ (laws) rather than kanones/ (rules), but almost all Orthodox conform to them. The dogmatic decisions of the Councils, though, are to be obeyed rather than to be treated as guidelines, since they are essential for the Church's unity.

What does Pedalion mean in English?
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A: Rudder

Problem: Georgian architecture:

In towns even most better-off people lived in terraced houses, which typically opened straight onto the street, often with a few steps up to the door. There was often an open space, protected by iron railings, dropping down to the basement level, with a discreet entrance down steps off the street for servants and deliveries; this is known as the "area". This meant that the ground floor front was now removed and protected from the street and encouraged the main reception rooms to move there from the floor above. Where, as often, a new street or set of streets was developed, the road and pavements were raised up, and the gardens or yards behind the houses at a lower level, usually representing the original one.

What were put behind the house on the same level?
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A:
unanswerable