In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
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Question: What vehicle could you have that you would need lower pressure boiler feed water?, Context: The Rankine cycle and most practical steam engines have a water pump to recycle or top up the boiler water, so that they may be run continuously. Utility and industrial boilers commonly use multi-stage centrifugal pumps; however, other types are used. Another means of supplying lower-pressure boiler feed water is an injector, which uses a steam jet usually supplied from the boiler. Injectors became popular in the 1850s but are no longer widely used, except in applications such as steam locomotives.

Answer: steam locomotives


Question: Why did Cubitt build the new wing?, Context: By 1847, the couple had found the palace too small for court life and their growing family, and consequently the new wing, designed by Edward Blore, was built by Thomas Cubitt, enclosing the central quadrangle. The large East Front, facing The Mall, is today the "public face" of Buckingham Palace, and contains the balcony from which the royal family acknowledge the crowds on momentous occasions and after the annual Trooping the Colour. The ballroom wing and a further suite of state rooms were also built in this period, designed by Nash's student Sir James Pennethorne.

Answer: the couple had found the palace too small for court life and their growing family


Question: Why are LED lights hard to make?, 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.

Answer:
development of more efficient phosphors