Please answer this: Extract the answer to the question from the following context. Question: Which of the following does not have elevators: guyed masts, safety lamps or towers? 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.
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Answer: safety lamps

Please answer this: Extract the answer to the question from the following context. Question: How big is the first library? Context: Nanjing Library, founded in 1907, houses more than 10 million volumes of printed materials and is the third largest library in China, after the National Library in Beijing and Shanghai Library. Other libraries, such as city-owned Jinling Library and various district libraries, also provide considerable amount of information to citizens. Nanjing University Library is the second largest university libraries in China after Peking University Library, and the fifth largest nationwide, especially in the number of precious collections.
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Answer: third largest library in China

Please answer this: Extract the answer to the question from the following context. Question: Which of the following is NOT a goal of phorphor LED development: higher light output, optical losses, or higher operation temperatures? Context: Among the challenges being faced to improve the efficiency of LED-based white light sources is the development of more efficient phosphors. As of 2010, the most efficient yellow phosphor is still the YAG phosphor, with less than 10% Stoke shift loss. Losses attributable to internal optical losses due to re-absorption in the LED chip and in the LED packaging itself account typically for another 10% to 30% of efficiency loss. Currently, in the area of phosphor LED development, much effort is being spent on optimizing these devices to higher light output and higher operation temperatures. For instance, the efficiency can be raised by adapting better package design or by using a more suitable type of phosphor. Conformal coating process is frequently used to address the issue of varying phosphor thickness.
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Answer:
optical losses