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

Example Input: Passage: Department stores today have sections that sell the following: clothing, furniture, home appliances, toys, cosmetics, gardening, toiletries, sporting goods, do it yourself, paint, and hardware and additionally select other lines of products such as food, books, jewelry, electronics, stationery, photographic equipment, baby products, and products for pets. Customers check out near the front of the store or, alternatively, at sales counters within each department. Some are part of a retail chain of many stores, while others may be independent retailers. In the 1970s, they came under heavy pressure from discounters. Since 2010, they have come under even heavier pressure from online stores such as Amazon.
Example Output: What sorts of departments might one see in a minor department store?

Example Input: Passage: About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km (1.0 mi) thick. The continent has about 90% of the world's ice (and thereby about 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 60 m (200 ft). In most of the interior of the continent, precipitation is very low, down to 20 mm (0.8 in) per year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys, the same effect occurs over a rock base, leading to a desiccated landscape.
Example Output:
What ice sheet covers all of Antarctica?