Problem: Railway electrification system:

DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.

The now-standard DC frequencies are what?
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A: unanswerable


Problem: Windows 8 introduced major changes to the operating system's platform and user interface to improve its user experience on tablets, where Windows was now competing with mobile operating systems, including Android and iOS. In particular, these changes included a touch-optimized Windows shell based on Microsoft's "Metro" design language, the Start screen (which displays programs and dynamically updated content on a grid of tiles), a new platform for developing apps with an emphasis on touchscreen input, integration with online services (including the ability to sync apps and settings between devices), and Windows Store, an online store for downloading and purchasing new software. Windows 8 added support for USB 3.0, Advanced Format hard drives, near field communications, and cloud computing. Additional security features were introduced, such as built-in antivirus software, integration with Microsoft SmartScreen phishing filtering service and support for UEFI Secure Boot on supported devices with UEFI firmware, to prevent malware from infecting the boot process.
What new security features does Windows 9 have?
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Answer: unanswerable


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Many sports are associated with New York's immigrant communities. Stickball, a street version of baseball, was popularized by youths in the 1930s, and a street in the Bronx was renamed Stickball Boulevard in the late 2000s to memorialize this.
A version of baseball played in city streets was nicknamed was in the 1930s?
A: Stickball


Context and question: Between 1993 and 1996, the FBI increased its counter-terrorism role in the wake of the first 1993 World Trade Center bombing in New York City, New York; the 1995 Oklahoma City bombing in Oklahoma City, Oklahoma; and the arrest of the Unabomber in 1996. Technological innovation and the skills of FBI Laboratory analysts helped ensure that the three cases were successfully prosecuted. Justice Department investigations into the FBI's roles in the Ruby Ridge and Waco incidents were found to be obstructed by agents within the Bureau. During the 1996 Summer Olympics in Atlanta, Georgia, the FBI was criticized for its investigation of the Centennial Olympic Park bombing. It has settled a dispute with Richard Jewell, who was a private security guard at the venue, along with some media organizations, in regard to the leaking of his name during the investigation.
What stopped the FBI from ensuring that these three cases were successfully prosecuted?
Answer: unanswerable


Question: Greek colonies and communities have been historically established on the shores of the Mediterranean Sea and Black Sea, but the Greek people have always been centered around the Aegean and Ionian seas, where the Greek language has been spoken since the Bronze Age. Until the early 20th century, Greeks were distributed between the Greek peninsula, the western coast of Asia Minor, the Black Sea coast, Cappadocia in central Anatolia, Egypt, the Balkans, Cyprus, and Constantinople. Many of these regions coincided to a large extent with the borders of the Byzantine Empire of the late 11th century and the Eastern Mediterranean areas of ancient Greek colonization. The cultural centers of the Greeks have included Athens, Thessalonica, Alexandria, Smyrna, and Constantinople at various periods.
Is there an answer to this question:  During which prehistoric age was the Greek language rejected?

Answer: unanswerable


Bell was a British subject throughout his early life in Scotland and later in Canada until 1882, when he became a naturalized citizen of the United States. In 1915, he characterized his status as: "I am not one of those hyphenated Americans who claim allegiance to two countries." Despite this declaration, Bell has been proudly claimed as a "native son" by all three countries he resided in: the United States, Canada, and the United Kingdom.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What was Bell's original nationality?
Ah, so..
British