Here is a question about this article: In the last two decades, photovoltaics (PV), also known as solar PV, has evolved from a pure niche market of small scale applications towards becoming a mainstream electricity source. A solar cell is a device that converts light directly into electricity using the photoelectric effect. The first solar cell was constructed by Charles Fritts in the 1880s. In 1931 a German engineer, Dr Bruno Lange, developed a photo cell using silver selenide in place of copper oxide. Although the prototype selenium cells converted less than 1% of incident light into electricity, both Ernst Werner von Siemens and James Clerk Maxwell recognized the importance of this discovery. Following the work of Russell Ohl in the 1940s, researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the crystalline silicon solar cell in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.56%. By 2012 available efficiencies exceed 20% and the maximum efficiency of research photovoltaics is over 40%.
What is the answer to this question: In what year was the crystalline silicon solar cell constructed?
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So... 1954

Here is a question about this article: FC Barcelona had a successful start in regional and national cups, competing in the Campionat de Catalunya and the Copa del Rey. In 1902, the club won its first trophy, the Copa Macaya, and participated in the first Copa del Rey, losing 12 to Bizcaya in the final. Hans Gamper now known as Joan Gamper became club president in 1908, finding the club in financial difficulty after not winning a competition since the Campionat de Catalunya in 1905. Club president on five separate occasions between 1908 and 1925, he spent 25 years in total at the helm. One of his main achievements was ensuring Barca acquire its own stadium and thus generate a stable income.
What is the answer to this question: Why did Gamper want Barcelona to acquire a stadium of its own?
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So... stable income

Here is a question about this article: For nearly 2000 years, Sanskrit was the language of a cultural order that exerted influence across South Asia, Inner Asia, Southeast Asia, and to a certain extent East Asia. A significant form of post-Vedic Sanskrit is found in the Sanskrit of Indian epic poetrythe Ramayana and Mahabharata. The deviations from Panini in the epics are generally considered to be on account of interference from Prakrits, or innovations, and not because they are pre-Paninian. Traditional Sanskrit scholars call such deviations arsa (), meaning 'of the rsis', the traditional title for the ancient authors. In some contexts, there are also more "prakritisms" (borrowings from common speech) than in Classical Sanskrit proper. Buddhist Hybrid Sanskrit is a literary language heavily influenced by the Middle Indo-Aryan languages, based on early Buddhist Prakrit texts which subsequently assimilated to the Classical Sanskrit standard in varying degrees.
What is the answer to this question: What are prakritisms?
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So...
borrowings from common speech