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.

Input: Consider Input: Passage: The average Mongol garrison family of the Yuan dynasty seems to have lived a life of decaying rural leisure, with income from the harvests of their Chinese tenants eaten up by costs of equipping and dispatching men for their tours of duty. The Mongols practiced debt slavery, and by 1290 in all parts of the Mongol Empire commoners were selling their children into slavery. Seeing this as damaging to the Mongol nation, Kublai in 1291 forbade the sale abroad of Mongols. Kublai wished to persuade the Chinese that he was becoming increasingly sinicized while maintaining his Mongolian credentials with his own people. He set up a civilian administration to rule, built a capital within China, supported Chinese religions and culture, and devised suitable economic and political institutions for the court. But at the same time he never abandoned his Mongolian heritage.

Output: By what year was selling children into slavery uncommon among the Mongols?


Input: Consider Input: Passage: As with most of Europe, prehistoric Britain and Ireland were covered with forest and swamp. Clearing began around 6000 BC and accelerated in medieval times. Despite this, Britain retained its primeval forests longer than most of Europe due to a small population and later development of trade and industry, and wood shortages were not a problem until the 17th century. By the 18th century, most of Britain's forests were consumed for shipbuilding or manufacturing charcoal and the nation was forced to import lumber from Scandinavia, North America, and the Baltic. Most forest land in Ireland is maintained by state forestation programmes. Almost all land outside urban areas is farmland. However, relatively large areas of forest remain in east and north Scotland and in southeast England. Oak, elm, ash and beech are amongst the most common trees in England. In Scotland, pine and birch are most common. Natural forests in Ireland are mainly oak, ash, wych elm, birch and pine. Beech and lime, though not native to Ireland, are also common there. Farmland hosts a variety of semi-natural vegetation of grasses and flowering plants. Woods, hedgerows, mountain slopes and marshes host heather, wild grasses, gorse and bracken.

Output: Ice and snow covered prehistoric Britain and what other country?


Input: Consider Input: Passage: In the late nineteenth century, two black Congressmen were elected from North Carolina's 2nd district, the last in 1898. George Henry White sought to promote civil rights for blacks and to challenge efforts by white Democrats to reduce black voting by new discriminatory laws. They were unsuccessful. In 1900, the state legislature passed a new constitution, with voter registration rules that disfranchised most blacks and many poor whites. The state succeeded in reducing black voting to zero by 1908. Loss of the ability to vote disqualified black men (and later women) from sitting on juries and serving in any office, local, state or federal. The rising black middle-class in Raleigh and other areas was politically silenced and shut out of local governance, and the Republican Party was no longer competitive. It was not until after federal civil rights legislation was passed in the mid-1960s that the majority of blacks in North Carolina would again be able to vote, sit on juries and serve in local offices. No African American was elected to Congress until 1992.


Output: When did the two black congressmen retire?