Problem: Railway electrification system:

Motors have very little room for electrical insulation so they generally have low voltage ratings. Because transformers (prior to the development of power electronics) cannot step down DC voltages, trains were supplied with a relatively low DC voltage that the motors can use directly. The most common DC voltages are listed in the previous section. Third (and fourth) rail systems almost always use voltages below 1 kV for safety reasons while overhead wires usually use higher voltages for efficiency. ("Low" voltage is relative; even 600 V can be instantly lethal when touched.)

What can step down DC voltages?
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A: unanswerable


Problem: London's defences were rapidly reorganised by General Pile, the Commander-in-Chief of Anti-Aircraft Command. The difference this made to the effectiveness of air defences is questionable. The British were still one-third below the establishment of heavy anti-aircraft artillery AAA (or ack-ack) in May 1941, with only 2,631 weapons available. Dowding had to rely on night fighters. From 1940 to 1941, the most successful night-fighter was the Boulton Paul Defiant; its four squadrons shot down more enemy aircraft than any other type. AA defences improved by better use of radar and searchlights. Over several months, the 20,000 shells spent per raider shot down in September 1940, was reduced to 4,087 in January 1941 and to 2,963 shells in February 1941.
The British were how far below the establishment of heavy anti-aircraft artillery?
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Answer: one-third


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
A Colorado study found bites in children were less severe than bites in adults. The incidence of dog bites in the US is 12.9 per 10,000 inhabitants, but for boys aged 5 to 9, the incidence rate is 60.7 per 10,000. Moreover, children have a much higher chance to be bitten in the face or neck. Sharp claws with powerful muscles behind them can lacerate flesh in a scratch that can lead to serious infections.
Out of 10,000 people, how many people are bitten by dogs in the United States?
A: 12.9


Context and question: Genetics compression algorithms are the latest generation of lossless algorithms that compress data (typically sequences of nucleotides) using both conventional compression algorithms and genetic algorithms adapted to the specific datatype. In 2012, a team of scientists from Johns Hopkins University published a genetic compression algorithm that does not use a reference genome for compression. HAPZIPPER was tailored for HapMap data and achieves over 20-fold compression (95% reduction in file size), providing 2- to 4-fold better compression and in much faster time than the leading general-purpose compression utilities. For this, Chanda, Elhaik, and Bader introduced MAF based encoding (MAFE), which reduces the heterogeneity of the dataset by sorting SNPs by their minor allele frequency, thus homogenizing the dataset. Other algorithms in 2009 and 2013 (DNAZip and GenomeZip) have compression ratios of up to 1200-fold—allowing 6 billion basepair diploid human genomes to be stored in 2.5 megabytes (relative to a reference genome or averaged over many genomes).
Who published a genetic compression algorithm that does not use diploids?
Answer: unanswerable


Question: Utrecht city has an active cultural life, and in the Netherlands is second only to Amsterdam. There are several theatres and theatre companies. The 1941 main city theatre was built by Dudok. Besides theatres there is a large number of cinemas including three arthouse cinemas. Utrecht is host to the international Early Music Festival (Festival Oude Muziek, for music before 1800) and the Netherlands Film Festival. The city has an important classical music hall Vredenburg (1979 by Herman Hertzberger). Its acoustics are considered among the best of the 20th-century original music halls.[citation needed] The original Vredenburg music hall has been redeveloped as part of the larger station area redevelopment plan and in 2014 has gained additional halls that allowed its merger with the rock club Tivoli and the SJU jazzpodium. There are several other venues for music throughout the city. Young musicians are educated in the conservatory, a department of the Utrecht School of the Arts. There is a specialised museum of automatically playing musical instruments.
Is there an answer to this question: Cultural life in Utrecht is second to 

Answer: Utrecht city has an active cultural life, and in the Netherlands is second only to Amsterdam


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Therapsids descended from pelycosaurs in the Middle Permian, about 265 million years ago, and became the dominant land vertebrates. They differ from basal eupelycosaurs in several features of the skull and jaws, including: larger temporal fenestrae and incisors which are equal in size. The therapsid lineage leading to mammals went through a series of stages, beginning with animals that were very like their pelycosaur ancestors and ending with probainognathian cynodonts, some of which could easily be mistaken for mammals. Those stages were characterized by:
At which group did Therapsids end with?
A:
probainognathian cynodonts