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.

Ex Input:
Passage: The best, worst and average case complexity refer to three different ways of measuring the time complexity (or any other complexity measure) of different inputs of the same size. Since some inputs of size n may be faster to solve than others, we define the following complexities:

Ex Output:
What are the three secondary expressions used to represent case complexity?

Ex Input:
Passage: In May 2007, YouTube launched its Partner Program, a system based on AdSense which allows the uploader of the video to share the revenue produced by advertising on the site. YouTube typically takes 45 percent of the advertising revenue from videos in the Partner Program, with 55 percent going to the uploader. There are over a million members of the YouTube Partner Program. According to TubeMogul, in 2013 a pre-roll advertisement on YouTube (one that is shown before the video starts) cost advertisers on average $7.60 per 1000 views. Usually no more than half of eligible videos have a pre-roll advertisement, due to a lack of interested advertisers. Assuming pre-roll advertisements on half of videos, a YouTube partner would earn 0.5 X $7.60 X 55% = $2.09 per 1000 views in 2013.

Ex Output:
What did YouTube launch in May 2013?

Ex Input:
Passage: The term "great power" was first used to represent the most important powers in Europe during the post-Napoleonic era. The "Great Powers" constituted the "Concert of Europe" and claimed the right to joint enforcement of the postwar treaties. The formalization of the division between small powers and great powers came about with the signing of the Treaty of Chaumont in 1814. Since then, the international balance of power has shifted numerous times, most dramatically during World War I and World War II. While some nations are widely considered to be great powers, there is no definitive list of them. In literature, alternative terms for great power are often world power or major power, but these terms can also be interchangeable with superpower.

Ex Output:
Why was the term formalization and division first used?