Problem: Electric motor:

Stepper motors are a type of motor frequently used when precise rotations are required. In a stepper motor an internal rotor containing PMs or a magnetically soft rotor with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the stepper motor may not rotate continuously; instead, it "steps"starts and then quickly stops againfrom one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down arbitrarily at any time.

When are stepper motors most useful?
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A: when precise rotations are required

Problem: PlayStation Network is the unified online multiplayer gaming and digital media delivery service provided by Sony Computer Entertainment for PlayStation 3 and PlayStation Portable, announced during the 2006 PlayStation Business Briefing meeting in Tokyo. The service is always connected, free, and includes multiplayer support. The network enables online gaming, the PlayStation Store, PlayStation Home and other services. PlayStation Network uses real currency and PlayStation Network Cards as seen with the PlayStation Store and PlayStation Home.
Along with being free and providing constant connectivity, what other feature does PS Network offer users?
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Answer: multiplayer support

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
On 15 August 2006, Brian May confirmed through his website and fan club that Queen + Paul Rodgers would begin producing their first studio album beginning in October, to be recorded at a "secret location". Queen + Paul Rodgers performed at the Nelson Mandela 90th Birthday Tribute held in Hyde Park, London on 27 June 2008, to commemorate Mandela's ninetieth birthday, and again promote awareness of the HIV/AIDS pandemic. The first Queen + Paul Rodgers album, titled The Cosmos Rocks, was released in Europe on 12 September 2008 and in the United States on 28 October 2008. Following the release of the album, the band again went on a tour through Europe, opening on Kharkiv's Freedom Square in front of 350,000 Ukrainian fans. The Kharkiv concert was later released on DVD. The tour then moved to Russia, and the band performed two sold-out shows at the Moscow Arena. Having completed the first leg of its extensive European tour, which saw the band play 15 sold-out dates across nine countries, the UK leg of the tour sold out within 90 minutes of going on sale and included three London dates, the first of which was The O2 on 13 October. The last leg of the tour took place in South America, and included a sold-out concert at the Estadio Jose Amalfitani, Buenos Aires.
In 2008 what disease did Queen perform benefit concerts for?
A: HIV/AIDS

Context and question: Chanakya, 4th Century BC Indian political philosopher. The Arthashastra provides an account of the science of politics for a wise ruler, policies for foreign affairs and wars, the system of a spy state and surveillance and economic stability of the state. Chanakya quotes several authorities including Bruhaspati, Ushanas, Prachetasa Manu, Parasara, and Ambi, and described himself as a descendant of a lineage of political philosophers, with his father Chanaka being his immediate predecessor. Another influential extant Indian treatise on political philosophy is the Sukra Neeti. An example of a code of law in ancient India is the Manusmrti or Laws of Manu.
Who is Prachetasa a descendant of?
Answer: unanswerable

Question: The early 1990s additionally saw the rise in mainstream US popularity for house music. Pop recording artist Madonna's 1990 single "Vogue" became an international hit single and topped the US charts. The single is credited as helping to bring house music to the US mainstream.
Is there an answer to this question: What decade did Madonna's music hit the mainstream in the US?

Answer: unanswerable

Beyonce announced a hiatus from her music career in January 2010, heeding her mother's advice, "to live life, to be inspired by things again". During the break she and her father parted ways as business partners. Beyonce's musical break lasted nine months and saw her visit multiple European cities, the Great Wall of China, the Egyptian pyramids, Australia, English music festivals and various museums and ballet performances.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): Which famous landmark did Beyonce see in China?
Ah, so..
the Great Wall of China