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: The noise-based speed is defined as the exposure that will lead to a given signal-to-noise ratio on individual pixels. Two ratios are used, the 40:1 ("excellent image quality") and the 10:1 ("acceptable image quality") ratio. These ratios have been subjectively determined based on a resolution of 70 pixels per cm (178 DPI) when viewed at 25 cm (9.8 inch) distance. The signal-to-noise ratio is defined as the standard deviation of a weighted average of the luminance and color of individual pixels. The noise-based speed is mostly determined by the properties of the sensor and somewhat affected by the noise in the electronic gain and AD converter.
Example Output: Which ratio was subjectively determined?

Example Input: Passage: The eleven prefecture-level divisions of Zhejiang are subdivided into 90 county-level divisions (36 districts, 20 county-level cities, 33 counties, and one autonomous county). Those are in turn divided into 1,570 township-level divisions (761 towns, 505 townships, 14 ethnic townships, and 290 subdistricts). Hengdian belongs to Jinhua, which is the largest base of shooting films and TV dramas in China. Hengdian is called "China's Hollywood".
Example Output: How many unprefecture-level divisions of Zhejiang are there?

Example Input: Passage: At the end of the Second World War, Canada possessed the fourth-largest air force and fifth-largest naval surface fleet in the world, as well as the largest volunteer army ever fielded. Conscription for overseas service was introduced only near the end of the war, and only 2,400 conscripts actually made it into battle. Originally, Canada was thought to have had the third-largest navy in the world, but with the fall of the Soviet Union, new data based on Japanese and Soviet sources found that to be incorrect.
Example Output:
When did Canada possess the fifth-largest air force?