input question: Question: "What makes a climbing elevator move?" Context: "A climbing elevator is a self-ascending elevator with its own propulsion. The propulsion can be done by an electric or a combustion engine. Climbing elevators are used in guyed masts or towers, in order to make easy access to parts of these constructions, such as flight safety lamps for maintenance. An example would be the Moonlight towers in Austin, Texas, where the elevator holds only one person and equipment for maintenance. The Glasgow Tower an observation tower in Glasgow, Scotland also makes use of two climbing elevators." Answer:???
output answer: its own propulsion

Question: "What does the E in NICE stand for?" Context: "In the UK, the Medicines and Healthcare Products Regulatory Agency approves drugs for use, though the evaluation is done by the European Medicines Agency, an agency of the European Union based in London. Normally an approval in the UK and other European countries comes later than one in the USA. Then it is the National Institute for Health and Care Excellence (NICE), for England and Wales, who decides if and how the National Health Service (NHS) will allow (in the sense of paying for) their use. The British National Formulary is the core guide for pharmacists and clinicians." Answer:
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Answer: Excellence

Q: Question: "Where did the invading force come from?" Context: "The United States accused Manuel Noriega's government in Panama of being a "narcokleptocracy", a corrupt government profiting on illegal drug trade. Later the U.S. invaded Panama and captured Noriega." Answer:
A: U.S

Question: Question: "When did the collection that grew to ten thousand volumes begin?" Context: "The first degrees from the college were awarded in 1849. The university was expanded with new buildings to accommodate more students and faculty. With each new president, new academic programs were offered and new buildings built to accommodate them. The original Main Building built by Sorin just after he arrived was replaced by a larger "Main Building" in 1865, which housed the university's administration, classrooms, and dormitories. Beginning in 1873, a library collection was started by Father Lemonnier. By 1879 it had grown to ten thousand volumes that were housed in the Main Building." Answer:
Answer: 1873

[Q]: Question: "what is been disussed in the passage?" Context: "In 2003, the ICZN ruled in its Opinion 2027 that if wild animals and their domesticated derivatives are regarded as one species, then the scientific name of that species is the scientific name of the wild animal. In 2005, the third edition of Mammal Species of the World upheld Opinion 2027 with the name Lupus and the note: "Includes the domestic dog as a subspecies, with the dingo provisionally separate - artificial variants created by domestication and selective breeding". However, Canis familiaris is sometimes used due to an ongoing nomenclature debate because wild and domestic animals are separately recognizable entities and that the ICZN allowed users a choice as to which name they could use, and a number of internationally recognized researchers prefer to use Canis familiaris." Answer:
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[A]: animals

Problem: Given the question: Question: "What is critical to have repetition pitch?" Context: "It is still possible for two sounds of indefinite pitch to clearly be higher or lower than one another. For instance, a snare drum sounds higher pitched than a bass drum though both have indefinite pitch, because its sound contains higher frequencies. In other words, it is possible and often easy to roughly discern the relative pitches of two sounds of indefinite pitch, but sounds of indefinite pitch do not neatly correspond to any specific pitch. A special type of pitch often occurs in free nature when sound reaches the ear of an observer directly from the source, and also after reflecting off a sound-reflecting surface. This phenomenon is called repetition pitch, because the addition of a true repetition of the original sound to itself is the basic prerequisite." Answer:
++++++++++++++++++++++++++++++++
The answer is:
sound-reflecting surface