Problem: Bilateral treaties are concluded between two states or entities. It is possible, however, for a bilateral treaty to have more than two parties; consider for instance the bilateral treaties between Switzerland and the European Union (EU) following the Swiss rejection of the European Economic Area agreement. Each of these treaties has seventeen parties. These however are still bilateral, not multilateral, treaties. The parties are divided into two groups, the Swiss ("on the one part") and the EU and its member states ("on the other part"). The treaty establishes rights and obligations between the Swiss and the EU and the member states severally—it does not establish any rights and obligations amongst the EU and its member states.[citation needed]
The bilateral treaties between Switzerland and the European Union followed the Swiss rejection of what?
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Answer: the European Economic Area agreement


Problem: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.
In how many ways can one define luminous efficacy of a light source?
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Answer: two ways


Problem: Following their wedding, the couple leased Windlesham Moor, near Windsor Castle, until 4 July 1949, when they took up residence at Clarence House in London. At various times between 1949 and 1951, the Duke of Edinburgh was stationed in the British Crown Colony of Malta as a serving Royal Navy officer. He and Elizabeth lived intermittently, for several months at a time, in the hamlet of Gwardamanġa, at Villa Guardamangia, the rented home of Philip's uncle, Lord Mountbatten. The children remained in Britain.
In what year did the Duke of Edinburgh become a Royal Navy officer?
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Answer:
unanswerable