Problem: On tracks that London Underground share with National Rail third-rail stock (the Bakerloo and District lines both have such sections), the centre rail is connected to the running rails, allowing both types of train to operate, at a compromise voltage of 660 V. Underground trains pass from one section to the other at speed; lineside electrical connections and resistances separate the two types of supply. These routes were originally solely electrified on the four-rail system by the LNWR before National Rail trains were rewired to their standard three-rail system to simplify rolling stock use.
The London Underground does not share tracks with whom?
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Answer: unanswerable

Problem: In 2007, the Institute for Policy Innovation (IPI) reported that music piracy took $12.5 billion from the U.S. economy. According to the study, musicians and those involved in the recording industry are not the only ones who experience losses attributed to music piracy. Retailers have lost over a billion dollars, while piracy has resulted in 46,000 fewer production-level jobs and almost 25,000 retail jobs. The U.S. government was also reported to suffer from music piracy, losing $422 million in tax revenue.
How many production-level jobs were lost?
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Answer: 46,000

Problem: Animals are also involved in the distribution of seeds. Fruit, which is formed by the enlargement of flower parts, is frequently a seed-dispersal tool that attracts animals to eat or otherwise disturb it, incidentally scattering the seeds it contains (see frugivory). Although many such mutualistic relationships remain too fragile to survive competition and to spread widely, flowering proved to be an unusually effective means of reproduction, spreading (whatever its origin) to become the dominant form of land plant life.
What did competition prove to be effective at doing?
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Answer:
unanswerable