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.

Example Input: Passage: In the former Soviet Union, electric traction eventually became somewhat more energy-efficient than diesel. Partly due to inefficient generation of electricity in the USSR (only 20.8% thermal efficiency in 1950 vs. 36.2% in 1975), in 1950 diesel traction was about twice as energy efficient as electric traction (in terms of net tonne-km of freight per kg of fuel). But as efficiency of electricity generation (and thus of electric traction) improved, by about 1965 electric railways became more efficient than diesel. After the mid 1970s electrics used about 25% less fuel per ton-km. However diesels were mainly used on single track lines with a fair amount of traffic  so that the lower fuel consumption of electrics may be in part due to better operating conditions on electrified lines (such as double tracking) rather than inherent energy efficiency. Nevertheless, the cost of diesel fuel was about 1.5 times more (per unit of heat energy content) than that of the fuel used in electric power plants (that generated electricity), thus making electric railways even more energy-cost effective.
Example Output: In the US, electric traction became more energy-efficient than what?

Example Input: Passage: All equipment must be suitable for a mixed-gender force. Combat helmets, rucksacks, combat boots, and flak jackets are designed to ensure women have the same level of protection and comfort as their male colleagues. The women's uniform is similar in design to the men's uniform, but conforms to the female figure, and is functional and practical. Women are also provided with an annual financial entitlement for the purchase of brassiere undergarments.
Example Output: What is a requirement for equipment for the CE?

Example Input: Passage: A fine tribute to the fall of Warsaw and history of Poland can be found in the Warsaw Uprising Museum and in the Katyń Museum which preserves the memory of the crime. The Warsaw Uprising Museum also operates a rare preserved and operating historic stereoscopic theatre, the Warsaw Fotoplastikon. The Museum of Independence preserves patriotic and political objects connected with Poland's struggles for independence. Dating back to 1936 Warsaw Historical Museum contains 60 rooms which host a permanent exhibition of the history of Warsaw from its origins until today.
Example Output:
Where can a tribute to the fall of Katyn be found?