Problem: Please answer a question about the following article about Electric motor:
Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. Sparks are created by the brushes making and breaking circuits through the rotor coils as the brushes cross the insulating gaps between commutator sections. Depending on the commutator design, this may include the brushes shorting together adjacent sections – and hence coil ends – momentarily while crossing the gaps. Furthermore, the inductance of the rotor coils causes the voltage across each to rise when its circuit is opened, increasing the sparking of the brushes. This sparking limits the maximum speed of the machine, as too-rapid sparking will overheat, erode, or even melt the commutator. The current density per unit area of the brushes, in combination with their resistivity, limits the output of the motor. The making and breaking of electric contact also generates electrical noise; sparking generates RFI. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance (on larger motors) or replacement (on small motors). The commutator assembly on a large motor is a costly element, requiring precision assembly of many parts. On small motors, the commutator is usually permanently integrated into the rotor, so replacing it usually requires replacing the whole rotor.
What motor components most need replacement and maintenance? 
A: Brushes


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Although it had equipment capable of doing serious damage, the problem for the Luftwaffe was its unclear strategy and poor intelligence. OKL had not been informed that Britain was to be considered a potential opponent until early 1938. It had no time to gather reliable intelligence on Britain's industries. Moreover, OKL could not settle on an appropriate strategy. German planners had to decide whether the Luftwaffe should deliver the weight of its attacks against a specific segment of British industry such as aircraft factories, or against a system of interrelated industries such as Britain's import and distribution network, or even in a blow aimed at breaking the morale of the British population. The Luftwaffe's strategy became increasingly aimless over the winter of 1940–1941. Disputes among the OKL staff revolved more around tactics than strategy. This method condemned the offensive over Britain to failure before it began.

What disagreements did the  Luftwaffe staff center around?
Answer: tactics


Problem: In the city, the population was spread out with 21.9% at age 19 and under, 14.3% from 20 to 24, 33.2% from 25 to 44, 20.4% from 45 to 64, and 10.1% who were 65 years of age or older. The median age was 30.8 years. For every 100 females, there were 92.0 males. For every 100 females age 18 and over, there were 89.9 males. There were 252,699 households, of which 20.4% had children under the age of 18 living in them, 25.5% were married couples living together, 16.3% had a female householder with no husband present, and 54.0% were non-families. 37.1% of all households were made up of individuals and 9.0% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 3.08.
What percentage of the City of Bostons population is 19 and under?
The answer is the following: 21.9%


The Great Plains is the broad expanse of flat land (a plain), much of it covered in prairie, steppe and grassland, that lies west of the Mississippi River tallgrass prairie states and east of the Rocky Mountains in the United States and Canada. This area covers parts, but not all, of the states of Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming, and the Canadian provinces of Alberta, Manitoba and Saskatchewan. The region is known for supporting extensive cattle ranching and dry farming.
what is the great plains?
broad expanse of flat land


Input: The Blitz
Five nights later, Birmingham was hit by 369 bombers from KG 54, KG 26, and KG 55. By the end of November, 1,100 bombers were available for night raids. An average of 200 were able to strike per night. This weight of attack went on for two months, with the Luftwaffe dropping 13,900 short tons (12,600 t) of bombs. In November 1940, 6,000 sorties and 23 major attacks (more than 100 tons of bombs dropped) were flown. Two heavy (50 short tons (45 t) of bombs) attacks were also flown. In December, only 11 major and five heavy attacks were made.

For how many months did the night raids continue for?
Output: two months


Problem: Please answer a question about the following article about Richmond, Virginia:
Electricity in the Richmond Metro area is provided by Dominion Virginia Power. The company, based in Richmond, is one of the nation's largest producers of energy, serving retail energy customers in nine states. Electricity is provided in the Richmond area primarily by the North Anna Nuclear Generating Station and Surry Nuclear Generating Station, as well as a coal-fired station in Chester, Virginia. These three plants provide a total of 4,453 megawatts of power. Several other natural gas plants provide extra power during times of peak demand. These include facilities in Chester, and Surry, and two plants in Richmond (Gravel Neck and Darbytown).
In what town is a coal-fired plant that provides power to Richmond located?
A:
Chester