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: The 197374 season saw the arrival of Johan Cruyff, who was bought for a world record 920,000 from Ajax. Already an established player with Ajax, Cruyff quickly won over the Barcelona fans when he told the European press that he chose Barcelona over Real Madrid because he could not play for a club associated with Francisco Franco. He further endeared himself when he named his son Jordi, after the local Catalan Saint George. Next to champions like Juan Manuel Asensi, Carles Rexach and Hugo Sotil, he helped the club win the 197374 season for the first time since 1960, defeating Real Madrid 50 at the Bernabeu along the way. He was crowned European Footballer of the Year in 1973 during his first season with Barcelona (his second Ballon d'Or win; he won his first while playing for Ajax in 1971). Cruyff received this prestigious award a third time (the first player to do so) in 1974, while he was still with Barcelona.

A: When did Johan Cruyff join Barcelona?
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Q: In addition to those actors who have headlined the series, others have portrayed versions of the Doctor in guest roles. Notably, in 2013, John Hurt guest-starred as a hitherto unknown incarnation of the Doctor known as the War Doctor in the run-up to the show's 50th anniversary special "The Day of the Doctor". He is shown in mini-episode "The Night of the Doctor" to have been retroactively inserted into the show's fictional chronology between McGann and Eccleston's Doctors, although his introduction was written so as not to disturb the established numerical naming of the Doctors. Another example is from the 1986 serial The Trial of a Time Lord, where Michael Jayston portrayed the Valeyard, who is described as an amalgamation of the darker sides of the Doctor's nature, somewhere between his twelfth and final incarnation.

A: Who played the War Doctor?
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Q: In the United States, August Vollmer introduced other reforms, including education requirements for police officers. O.W. Wilson, a student of Vollmer, helped reduce corruption and introduce professionalism in Wichita, Kansas, and later in the Chicago Police Department. Strategies employed by O.W. Wilson included rotating officers from community to community to reduce their vulnerability to corruption, establishing of a non-partisan police board to help govern the police force, a strict merit system for promotions within the department, and an aggressive recruiting drive with higher police salaries to attract professionally qualified officers. During the professionalism era of policing, law enforcement agencies concentrated on dealing with felonies and other serious crime, rather than broader focus on crime prevention.

A:
Who was O.W. Wilson a student of?
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