This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
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Question: Passage: The first extant Estonian book is a bilingual German-Estonian translation of the Lutheran catechism by S. Wanradt and J. Koell dating to 1535, during the Protestant Reformation period. An Estonian grammar book to be used by priests was printed in German in 1637. The New Testament was translated into southern Estonian in 1686 (northern Estonian, 1715). The two languages were united based on northern Estonian by Anton thor Helle.

Answer: Who wrote the last Estonian book? 


Question: Passage: The climate in Southeast Alaska is a mid-latitude oceanic climate (Köppen climate classification: Cfb) in the southern sections and a subarctic oceanic climate (Köppen Cfc) in the northern parts. On an annual basis, Southeast is both the wettest and warmest part of Alaska with milder temperatures in the winter and high precipitation throughout the year. Juneau averages over 50 in (130 cm) of precipitation a year, and Ketchikan averages over 150 in (380 cm). This is also the only region in Alaska in which the average daytime high temperature is above freezing during the winter months.

Answer: How much precipitation doesn't Juneau receive each year?


Question: Passage: Data compression can be viewed as a special case of data differencing: Data differencing consists of producing a difference given a source and a target, with patching producing a target given a source and a difference, while data compression consists of producing a compressed file given a target, and decompression consists of producing a target given only a compressed file. Thus, one can consider data compression as data differencing with empty source data, the compressed file corresponding to a "difference from nothing." This is the same as considering absolute entropy (corresponding to data compression) as a special case of relative entropy (corresponding to data differencing) with no initial data.

Answer:
What can be looked at as a special case of relative entropy?