Input: Article: The English language has been official in the state of Oklahoma since 2010. The variety of North American English spoken is called Oklahoma English, and this dialect is quite diverse with its uneven blending of features of North Midland, South Midland, and Southern dialects. In 2000, 2,977,187 Oklahomans92.6% of the resident population five years or olderspoke only English at home, a decrease from 95% in 1990. 238,732 Oklahoma residents reported speaking a language other than English in the 2000 census, about 7.4% of the total population of the state. Spanish is the second most commonly spoken language in the state, with 141,060 speakers counted in 2000. The next most commonly spoken language is Cherokee, with about 22,000 speakers living within the Cherokee Nation tribal jurisdiction area of eastern Oklahoma. Cherokee is an official language in the Cherokee Nation tribal jurisdiction area and in the United Keetoowah Band of Cherokee Indians.

Now answer this question: When did Oklahoma declare an official language?

Output: 2010

Input: Article: The decision to change strategy is sometimes claimed as a major mistake by the Oberkommando der Luftwaffe (OKL). It is argued that persisting with attacks on RAF airfields might have won air superiority for the Luftwaffe. Others argue that the Luftwaffe made little impression on Fighter Command in the last week of August and first week of September and that the shift in strategy was not decisive. It has also been argued that it was doubtful the Luftwaffe could have won air superiority before the "weather window" began to deteriorate in October. It was also possible, if RAF losses became severe, that they could pull out to the north, wait for the German invasion, then redeploy southward again. Other historians argue that the outcome of the air battle was irrelevant; the massive numerical superiority of British naval forces and the inherent weakness of the Kriegsmarine would have made the projected German invasion, Unternehmen Seelowe (Operation Sea Lion), a disaster with or without German air superiority.

Now answer this question: What does OKL stand for?

Output: Oberkommando der Luftwaffe

Input: Article: This technique was very expensive, though, and could not be used for applications such as telemedicine, distance education, and business meetings. Attempts at using normal telephony networks to transmit slow-scan video, such as the first systems developed by AT&T Corporation, first researched in the 1950s, failed mostly due to the poor picture quality and the lack of efficient video compression techniques. The greater 1 MHz bandwidth and 6 Mbit/s bit rate of the Picturephone in the 1970s also did not achieve commercial success, mostly due to its high cost, but also due to a lack of network effect with only a few hundred Picturephones in the world, users had extremely few contacts they could actually call to, and interoperability with other videophone systems would not exist for decades.

Now answer this question: When was the first slow-scan video systems researched?

Output:
the 1950s