Problem: Anti-aircraft warfare:

The Germans developed massive reinforced concrete blockhouses, some more than six stories high, which were known as Hochbunker "High Bunkers" or "Flakturme" flak towers, on which they placed anti-aircraft artillery. Those in cities attacked by the Allied land forces became fortresses. Several in Berlin were some of the last buildings to fall to the Soviets during the Battle of Berlin in 1945. The British built structures such as the Maunsell Forts in the North Sea, the Thames Estuary and other tidal areas upon which they based guns. After the war most were left to rot. Some were outside territorial waters, and had a second life in the 1960s as platforms for pirate radio stations.

What structure did the British build in the North Sea?
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A: Maunsell Forts

Problem: Muawiyah also encouraged peaceful coexistence with the Christian communities of Syria, granting his reign with "peace and prosperity for Christians and Arabs alike", and one of his closest advisers was Sarjun, the father of John of Damascus. At the same time, he waged unceasing war against the Byzantine Roman Empire. During his reign, Rhodes and Crete were occupied, and several assaults were launched against Constantinople. After their failure, and faced with a large-scale Christian uprising in the form of the Mardaites, Muawiyah concluded a peace with Byzantium. Muawiyah also oversaw military expansion in North Africa (the foundation of Kairouan) and in Central Asia (the conquest of Kabul, Bukhara, and Samarkand).
Who discouraged peaceful coexistence with the Christians in Syria?
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Answer: unanswerable

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The Gregorian calendar improves the approximation made by the Julian calendar by skipping three Julian leap days in every 400 years, giving an average year of 365.2425 mean solar days long. This approximation has an error of about one day per 3,300 years with respect to the mean tropical year. However, because of the precession of the equinoxes, the error with respect to the vernal equinox (which occurs, on average, 365.24237 days apart near 2000) is 1 day every 7,700 years, assuming a constant time interval between vernal equinoxes, which is not true. By any criterion, the Gregorian calendar is substantially more accurate than the 1 day in 128 years error of the Julian calendar (average year 365.25 days).
How many days must be skipped to align the calendar with mean solar days in a year?
A: three Julian leap days

Context and question: Starting in the 1890s and stretching in some places to the early 1910s, gold rushes in Alaska and the nearby Yukon Territory brought thousands of miners and settlers to Alaska. Alaska was officially incorporated as an organized territory in 1912. Alaska's capital, which had been in Sitka until 1906, was moved north to Juneau. Construction of the Alaska Governor's Mansion began that same year. European immigrants from Norway and Sweden also settled in southeast Alaska, where they entered the fishing and logging industries.
What year was Alaska officially incorporated as a territory?
Answer: 1912

Question: The first season of American Idol debuted as a summer replacement show in June 2002 on the Fox network. It was co-hosted by Ryan Seacrest and Brian Dunkleman.
Is there an answer to this question: What year did American Idol first debut?

Answer: 2002

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
During the Cambrian period, Gondwana had a mild climate. West Antarctica was partially in the Northern Hemisphere, and during this period large amounts of sandstones, limestones and shales were deposited. East Antarctica was at the equator, where sea floor invertebrates and trilobites flourished in the tropical seas. By the start of the Devonian period (416 Ma), Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. Sand and silts were laid down in what is now the Ellsworth, Horlick and Pensacola Mountains. Glaciation began at the end of the Devonian period (360 Ma), as Gondwana became centered on the South Pole and the climate cooled, though flora remained. During the Permian period, the land became dominated by seed plants such as Glossopteris, a pteridosperm which grew in swamps. Over time these swamps became deposits of coal in the Transantarctic Mountains. Towards the end of the Permian period, continued warming led to a dry, hot climate over much of Gondwana.
What life florishes in East Antarctica's tropical seas?
A:
unanswerable