Context and question: Raleigh (/ˈrɑːli/; RAH-lee) is the capital of the state of North Carolina as well as the seat of Wake County in the United States. It is the second most populous city in North Carolina, after Charlotte. Raleigh is known as the "City of Oaks" for its many oak trees, which line the streets in the heart of the city. The city covers a land area of 142.8 square miles (370 km2). The U.S. Census Bureau estimated the city's population to be 439,896 as of July 1, 2014. It is also one of the fastest-growing cities in the country. The city of Raleigh is named after Sir Walter Raleigh, who established the lost Roanoke Colony in present-day Dare County.
What city is known as the City of Elks? 
Answer: unanswerable
Context and question: Van Praag states that the Ming court established diplomatic delegations with Tibet merely to secure urgently needed horses. Wang and Nyima argue that these were not diplomatic delegations at all, that Tibetan areas were ruled by the Ming since Tibetan leaders were granted positions as Ming officials, that horses were collected from Tibet as a mandatory "corvée" tax, and therefore Tibetans were "undertaking domestic affairs, not foreign diplomacy". Sperling writes that the Ming simultaneously bought horses in the Kham region while fighting Tibetan tribes in Amdo and receiving Tibetan embassies in Nanjing. He also argues that the embassies of Tibetan lamas visiting the Ming court were for the most part efforts to promote commercial transactions between the lamas' large, wealthy entourage and Ming Chinese merchants and officials. Kolmaš writes that while the Ming maintained a laissez-faire policy towards Tibet and limited the numbers of the Tibetan retinues, the Tibetans sought to maintain a tributary relationship with the Ming because imperial patronage provided them with wealth and power. Laird writes that Tibetans eagerly sought Ming court invitations since the gifts the Tibetans received for bringing tribute were much greater in value than the latter. As for the Yongle Emperor's gifts to his Tibetan and Nepalese vassals such as silver wares, Buddha relics, utensils for Buddhist temples and religious ceremonies, and gowns and robes for monks, Tsai writes "in his effort to draw neighboring states to the Ming orbit so that he could bask in glory, the Yongle Emperor was quite willing to pay a small price". The Information Office of the State Council of the PRC lists the Tibetan tribute items as oxen, horses, camels, sheep, fur products, medical herbs, Tibetan incenses, thangkas (painted scrolls), and handicrafts; while the Ming awarded Tibetan tribute-bearers an equal value of gold, silver, satin and brocade, bolts of cloth, grains, and tea leaves. Silk workshops during the Ming also catered specifically to the Tibetan market with silk clothes and furnishings featuring Tibetan Buddhist iconography.
Why does Van Praag believe the Ming court set up a diplomatic delegation with Tibet?
Answer: to secure urgently needed horses
Context and question: Some video compression schemes typically operate on square-shaped groups of neighboring pixels, often called macroblocks. These pixel groups or blocks of pixels are compared from one frame to the next, and the video compression codec sends only the differences within those blocks. In areas of video with more motion, the compression must encode more data to keep up with the larger number of pixels that are changing. Commonly during explosions, flames, flocks of animals, and in some panning shots, the high-frequency detail leads to quality decreases or to increases in the variable bitrate.
What only sends the differences within those pixels and blocks?
Answer:
macroblocks