input question: Extract the answer to the question from the following context. Question: What structural elements allow a climbing elevator to 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.???
output answer: an electric or a combustion engine

input question: Extract the answer to the question from the following context. Question: What was studied as it was suspended? Context: After the war, Feynman declined an offer from the Institute for Advanced Study in Princeton, New Jersey, despite the presence there of such distinguished faculty members as Albert Einstein, Kurt Gödel and John von Neumann. Feynman followed Hans Bethe, instead, to Cornell University, where Feynman taught theoretical physics from 1945 to 1950. During a temporary depression following the destruction of Hiroshima by the bomb produced by the Manhattan Project, he focused on complex physics problems, not for utility, but for self-satisfaction. One of these was analyzing the physics of a twirling, nutating dish as it is moving through the air. His work during this period, which used equations of rotation to express various spinning speeds, proved important to his Nobel Prize–winning work, yet because he felt burned out and had turned his attention to less immediately practical problems, he was surprised by the offers of professorships from other renowned universities.???
output answer: nutating dish

input question: Extract the answer to the question from the following context. Question: What was the timespan during which the Jewish population doubled? Context: By the 1st century, Babylonia, to which Jews migrated to after the Babylonian conquest as well as after the Bar Kokhba revolt in 135 CE, already held a speedily growing population of an estimated 1,000,000 Jews, which increased to an estimated 2 million  between the years 200 CE – 500 CE, both by natural growth and by immigration of more Jews from the Land of Israel, making up about 1/6 of the world Jewish population at that era. At times conversion has accounted for a part of Jewish population growth. Some have claimed that in the 1st century of the Christian era, for example, the population more than doubled, from four to 8–10 million within the confines of the Roman Empire, in good part as a result of a wave of conversion.???
output answer: 200 CE – 500 CE

input question: Extract the answer to the question from the following context. Question: What caused the city to be so badly damaged? Context: Pockets of Georgian architecture survived the war, but much of the city was levelled. There has been extensive redevelopment since World War II. Increasing traffic congestion in the 1920s led to partial demolition of medieval walls around the Bargate in 1932 and 1938. However a large portion of those walls remain.???
output answer:
the war