instruction:
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.
question:
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.
answer:
In what year was a large scale solar distillation project constructed in Las Salinas?

question:
Two years later, the Royal African Company was inaugurated, receiving from King Charles a monopoly of the trade to supply slaves to the British colonies of the Caribbean. From the outset, slavery was the basis of the British Empire in the West Indies. Until the abolition of the slave trade in 1807, Britain was responsible for the transportation of 3.5 million African slaves to the Americas, a third of all slaves transported across the Atlantic. To facilitate this trade, forts were established on the coast of West Africa, such as James Island, Accra and Bunce Island. In the British Caribbean, the percentage of the population of African descent rose from 25 percent in 1650 to around 80 percent in 1780, and in the 13 Colonies from 10 percent to 40 percent over the same period (the majority in the southern colonies). For the slave traders, the trade was extremely profitable, and became a major economic mainstay for such western British cities as Bristol and Liverpool, which formed the third corner of the so-called triangular trade with Africa and the Americas. For the transported, harsh and unhygienic conditions on the slaving ships and poor diets meant that the average mortality rate during the Middle Passage was one in seven.
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Which company had monopoly of the trade to supply slaves to the British colonies of the Caribbean?

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Instead, Nanjing, as a popular tourist destination, hosts a series of government-organised events throughout the year. The annual International Plum Blossom Festival held in Plum Blossom Hill, the largest plum collection in China, attracts thousands of tourists both domestically and internationally. Other events include Nanjing Baima Peach Blossom and Kite Festival, Jiangxin Zhou Fruit Festival and Linggu Temple Sweet Osmanthus Festival.
answer:
What city is considered to be a place that is popular with tourists?