This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Q: Studies by Nathaniel Kleitman in 1938 and by Derk-Jan Dijk and Charles Czeisler in the 1990s put human subjects on enforced 28-hour sleepwake cycles, in constant dim light and with other time cues suppressed, for over a month. Because normal people cannot entrain to a 28-hour day in dim light if at all,[citation needed] this is referred to as a forced desynchrony protocol. Sleep and wake episodes are uncoupled from the endogenous circadian period of about 24.18 hours and researchers are allowed to assess the effects of circadian phase on aspects of sleep and wakefulness including sleep latency and other functions.[page needed]

A: What time cycle did studies in 1938 and 1990s use on humans?
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Q: In June 2009 the first major building work at the abbey for 250 years was proposed. A coronaa crown-like architectural featurewas intended to be built around the lantern over the central crossing, replacing an existing pyramidal structure dating from the 1950s. This was part of a wider 23m development of the abbey expected to be completed in 2013. On 4 August 2010 the Dean and Chapter announced that, "[a]fter a considerable amount of preliminary and exploratory work", efforts toward the construction of a corona would not be continued. In 2012, architects Panter Hudspith completed refurbishment of the 14th-century food-store originally used by the abbey's monks, converting it into a restaurant with English Oak furniture by Covent Garden-based furniture makers Luke Hughes and Company.

A: What was proposed for the abbey in June 2009?
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Q: Solar distillation can be used to make saline or brackish water potable. The first recorded instance of this was by 16th-century Arab alchemists. A large-scale solar distillation project was first constructed in 1872 in the Chilean mining town of Las Salinas. The plant, which had solar collection area of 4,700 m2 (51,000 sq ft), could produce up to 22,700 L (5,000 imp gal; 6,000 US gal) per day and operate for 40 years. Individual still designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect. These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.

A:
In what year was a large scale solar distillation project constructed in Las Salinas?
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