Problem: Railway electrification system:

A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.

What requires insignificant capital expenditure?
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A: unanswerable


Problem: Classical music:

In 1996–1997, a research study was conducted on a large population of middle age students in the Cherry Creek School District in Denver, Colorado, USA. The study showed that students who actively listen to classical music before studying had higher academic scores. The research further indicated that students who listened to the music prior to an examination also had positively elevated achievement scores. Students who listened to rock-and-roll or country had moderately lower scores. The study further indicated that students who used classical during the course of study had a significant leap in their academic performance; whereas, those who listened to other types of music had significantly lowered academic scores. The research was conducted over several schools within the Cherry Creek School District and was conducted through University of Colorado. This study is reflective of several recent studies (i.e. Mike Manthei and Steve N. Kelly of the University of Nebraska at Omaha; Donald A. Hodges and Debra S. O'Connell of the University of North Carolina at Greensboro; etc.) and others who had significant results through the discourse of their work.

What happened to the scores of students who listened to rock and roll or country?
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A: moderately lower


Problem: Bern:

The city grew out towards the west of the boundaries of the peninsula formed by the River Aare. The Zytglogge tower marked the western boundary of the city from 1191 until 1256, when the Käfigturm took over this role until 1345. It was, in turn, succeeded by the Christoffelturm (formerly located close to the site of the modern-day railway station) until 1622. During the time of the Thirty Years' War, two new fortifications – the so-called big and small Schanze (entrenchment) – were built to protect the whole area of the peninsula.

What tower took over after Zytglogge?
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A: Käfigturm


Problem: Muslim world:

Distinguishing motifs of Islamic architecture have always been ordered repetition, radiating structures, and rhythmic, metric patterns. In this respect, fractal geometry has been a key utility, especially for mosques and palaces. Other features employed as motifs include columns, piers and arches, organized and interwoven with alternating sequences of niches and colonnettes. The role of domes in Islamic architecture has been considerable. Its usage spans centuries, first appearing in 691 with the construction of the Dome of the Rock mosque, and recurring even up until the 17th century with the Taj Mahal. And as late as the 19th century, Islamic domes had been incorporated into European architecture.

When was the Taj Mahal constructed?
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A:
17th century