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Poland's successive kings granted privileges to the nobility at the time of their election to the throne (the privileges being specified in the king-elect's Pacta conventa) and at other times in exchange for ad hoc permission to raise an extraordinary tax or a pospolite ruszenie.

When did kings grant privileges to the nobles?
Answer: at the time of their election to the throne
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In 1958, the Soviet Union developed ransformator (Russian: , meaning Transformer), the first high-resolution (definition) television system capable of producing an image composed of 1,125 lines of resolution aimed at providing teleconferencing for military command. It was a research project and the system was never deployed by either the military or consumer broadcasting.

In the end what was the Soviet Union's Transformator system used for?
Answer: a research project
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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.

What is an example of a solar distillation design?
Answer:
single-slope