TASK DEFINITION: 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.
PROBLEM: Passage: Unlike Modern English, Old English is a language rich in morphological diversity. It maintains several distinct cases: the nominative, accusative, genitive, dative and (vestigially) instrumental. The only remnants of this system in Modern English are in the forms of a few pronouns (such as I/me/mine, she/her, who/whom/whose) and in the possessive ending -'s, which derives from the old (masculine and neuter) genitive ending -es. In Old English, however, nouns and their modifying words take appropriate endings depending on their case.

SOLUTION: What kind of diversity is found in Modern English?

PROBLEM: Passage: In Armenia Russian has no official status, but it's recognised as a minority language under the Framework Convention for the Protection of National Minorities. According to estimates from Demoskop Weekly, in 2004 there were 15,000 native speakers of Russian in the country, and 1 million active speakers. 30% of the population was fluent in Russian in 2006, and 2% used it as the main language with family, friends or at work. Russian is spoken by 1.4% of the population according to a 2009 estimate from the World Factbook.

SOLUTION: How many people read Demoskop Weekly in 2004?

PROBLEM: Passage: Other supportive evidence includes: a 20% difference in peak expiratory flow rate on at least three days in a week for at least two weeks, a 20% improvement of peak flow following treatment with either salbutamol, inhaled corticosteroids or prednisone, or a 20% decrease in peak flow following exposure to a trigger. Testing peak expiratory flow is more variable than spirometry, however, and thus not recommended for routine diagnosis. It may be useful for daily self-monitoring in those with moderate to severe disease and for checking the effectiveness of new medications. It may also be helpful in guiding treatment in those with acute exacerbations.

SOLUTION:
What is not as stable as prednisone for a routine diagnosis?