instruction:
In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
question:
Passage: A five-movement ballet occurred somewhere in Act II, staged by W. H. Payne. A heading in the libretto, "Chorus and Ballet", attaches it to the last section of the finale but does not indicate how it figured in the plot. Most press accounts placed it at about this point, although some placed it slightly earlier in the act. At some performances, the ballet was performed in Act I, but it was certainly in Act II on opening night, and it seems finally to have settled there.In 1990, Roderick Spencer and Selwyn Tillett discovered the ballet from Act II of Thespis. Two of the five movements, in the same hand that had copied the score of "Climbing over rocky mountain", were found together with the surviving performance materials for Sullivan's 1864 ballet, L'Île Enchantée. Another section was found in the material for his 1897 ballet, Victoria and Merrie England. The page numbering of the surviving three sections gave approximate lengths for the missing pieces, and a contemporary engraving, seen at left, along with other circumstantial evidence, allowed plausible identifications of the two remaining movements: a dragon costume, used nowhere in the libretto, is presumably from the ballet, and the harp visible in the orchestra pit was an unusual instrument for the Gaiety's orchestra. Movements of appropriate length that made sense of these oddities were found in Sullivan's other ballets, and the reconstructed ballet has been recorded twice on CD.
Sullivan tended to re-use his ballet music. Of the five movements that Tillett and Spencer identified, only one (the Waltz, No. 3) is not known to have been used in any other work. Three of the movements had previously been used in L'Île Enchantée. Two of those, and one other, were eventually re-used in Victoria and Merrie England. One was also used in his incidental music to Macbeth. Sullivan was asked in 1889 to supply a ballet for a French-language production of The Mikado in Brussels, which he duly did. Tillett suggests that the Thespis ballet was almost certainly the music that Sullivan provided, given that it was the only ballet that he wrote for use in an opera, and that three weeks after producing The Gondoliers he is unlikely to have written something original.
answer:
What were the name of the two movements discovered by Spencer and Tillett?


question:
Passage: The management of Rockefeller Center shifted around this time. In November 1936, John Todd was featured in two New Yorker articles that emphasized his role in the complex's construction. At the same time, Nelson was gaining clout within Rockefeller Center Inc., and he disagreed with nearly all of Todd's suggestions. Nelson's father, John, was relinquishing his responsibilities, since the Rockefeller family's youngest son David had moved out of the family home at 10 West 54th Street, and John was now focusing on his own personal life. By April 1937, Todd regretted his decision to be featured in The New Yorker. In March 1938, Nelson became the president of Rockefeller Center Inc. He then fired Todd as the complex's manager and appointed Hugh Robertson in his place. Nelson and Robertson wanted to avoid workers' strikes, which would delay the completion of construction. Nelson, Robertson, and the workers' unions agreed to a contract in which the unions would not strike, Robertson would not lock out union workers, and both would agree to arbitration if a labor dispute arose. Rockefeller Center was one of Nelson's primary business ventures until 1958, when he was elected Governor of New York.Public relations officials were hired to advertise the different parts of the complex, such as the gardens and the plaza. Merle Crowell set up a viewing platform on the east side of Rockefeller Center and founded the facetious "Sidewalk Superintendents' Club" so the public could view construction.
answer:
What is the first name of the person who appointed Hugh Robertson as the complex manager?


question:
Passage: The origins of the Early Netherlandish school lie in the miniature paintings of the late Gothic period.  This was first seen in manuscript illumination, which after 1380 conveyed new levels of realism, perspective and skill in rendering colour, peaking with the Limbourg brothers and the Netherlandish artist known as Hand G, to whom the most significant leaves of the Turin-Milan Hours are usually attributed. Although his identity has not been definitively established, Hand G, who contributed c. 1420, is thought to have been either Jan van Eyck or his brother Hubert. According to Georges Hulin de Loo, Hand G's contributions to the Turin-Milan Hours "constitute the most marvelous group of paintings that have ever decorated any book, and, for their period, the most astounding work known to the history of art".Jan van Eyck's use of oil as a medium was a significant development, allowing artists far greater manipulation of paint. The 16th-century art historian Giorgio Vasari claimed van Eyck invented the use of oil paint; a claim that, while exaggerated, indicates the extent to which van Eyck helped disseminate the technique. Van Eyck employed a new level of virtuosity, mainly from taking advantage of the fact that oil dries so slowly; this gave him more time and more scope for blending and mixing layers of different pigments, and his technique was quickly adopted and refined by both Robert Campin and Rogier van der Weyden. These three artists are considered the first rank and most influential of the early generation of Early Netherlandish painters. Their influence was felt across northern Europe, from Bohemia and Poland in the east to Austria and Swabia in the south.
answer:

What is the first name of the person who the 16th-century art historian Giorgio Vasari claimed invented the use of oil paint?