Problem: Glacier:

Glacial bodies larger than 50,000 km2 (19,000 sq mi) are called ice sheets or continental glaciers. Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of fresh water, enough that if both melted, global sea levels would rise by over 70 m (230 ft). Portions of an ice sheet or cap that extend into water are called ice shelves; they tend to be thin with limited slopes and reduced velocities. Narrow, fast-moving sections of an ice sheet are called ice streams. In Antarctica, many ice streams drain into large ice shelves. Some drain directly into the sea, often with an ice tongue, like Mertz Glacier.

What are ice sheets that cover the sea called?
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A: unanswerable

Problem: In England, Presbyterianism was established in secret in 1592. Thomas Cartwright is thought to be the first Presbyterian in England. Cartwright's controversial lectures at Cambridge University condemning the episcopal hierarchy of the Elizabethan Church led to his deprivation of his post by Archbishop John Whitgift and his emigration abroad. Between 1645 and 1648, a series of ordinances of the Long Parliament established Presbyterianism as the polity of the Church of England. Presbyterian government was established in London and Lancashire and in a few other places in England, although Presbyterian hostility to the execution of Charles I and the establishment of the republican Commonwealth of England meant that Parliament never enforced the Presbyterian system in England. The re-establishment of the monarchy in 1660 brought the return of Episcopal church government in England (and in Scotland for a short time); but the Presbyterian church in England continued in Non-Conformity, outside of the established church. In 1719 a major split, the Salter's Hall controversy, occurred; with the majority siding with nontrinitarian views. Thomas Bradbury published several sermons bearing on the controversy, and in 1719, "An answer to the reproaches cast on the dissenting ministers who subscribed their belief of the Eternal Trinity.". By the 18th century many English Presbyterian congregations had become Unitarian in doctrine.
What was reestablished in 1719?
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Answer: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
A union planned to protest at the relay for better living conditions. Hong Kong legislator Michael Mak Kwok-fung and activist Chan Cheong, both members of the League of Social Democrats, were not allowed to enter Macau.
Who was Michael Mak Kwok-fung?
A: Hong Kong legislator

Context and question: European art music is largely distinguished from many other non-European and popular musical forms by its system of staff notation, in use since about the 16th century. Western staff notation is used by composers to prescribe to the performer the pitches (e.g., melodies, basslines and/or chords), tempo, meter and rhythms for a piece of music. This leaves less room for practices such as improvisation and ad libitum ornamentation, which are frequently heard in non-European art music and in popular music styles such as jazz and blues. Another difference is that whereas most popular styles lend themselves to the song form, classical music has been noted for its development of highly sophisticated forms of instrumental music such as the concerto, symphony, sonata, and mixed vocal and instrumental styles such as opera which, since they are written down, can attain a high level of complexity.
How long has the system of staff notation been in use?
Answer: since about the 16th century

Question: Though there is no doubt that the demographic crisis of the 14th century caused a dramatic fall in production and commerce in absolute terms, there has been a vigorous historical debate over whether the decline was greater than the fall in population. While the older orthodoxy held that the artistic output of the Renaissance was a result of greater opulence, more recent studies have suggested that there might have been a so-called 'depression of the Renaissance'. In spite of convincing arguments for the case, the statistical evidence is simply too incomplete for a definite conclusion to be made.
Is there an answer to this question: What is the alternative to the theory that the Renaissance was a time of no opulence?

Answer: unanswerable

Problem: Southern Europe:

The period known as the Crusades, a series of religiously motivated military expeditions originally intended to bring the Levant back into Christian rule, began. Several Crusader states were founded in the eastern Mediterranean. These were all short-lived. The Crusaders would have a profound impact on many parts of Europe. Their Sack of Constantinople in 1204 brought an abrupt end to the Byzantine Empire. Though it would later be re-established, it would never recover its former glory. The Crusaders would establish trade routes that would develop into the Silk Road and open the way for the merchant republics of Genoa and Venice to become major economic powers. The Reconquista, a related movement, worked to reconquer Iberia for Christendom.

Which two cities benefited greatly from the activities of Crusaders?
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A:
Genoa and Venice