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.

Q: Passage: There is no natural source for green food colorings which has been approved by the US Food and Drug Administration. Chlorophyll, the E numbers E140 and E141, is the most common green chemical found in nature, and only allowed in certain medicines and cosmetic materials. Quinoline Yellow (E104) is a commonly used coloring in the United Kingdom but is banned in Australia, Japan, Norway and the United States. Green S (E142) is prohibited in many countries, for it is known to cause hyperactivity, asthma, urticaria, and insomnia.

A: Which two E numbers have been approved by the FDA?
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Q: Passage: In 1661 another Jesuit, Johann Grueber, crossed Tibet from Sining to Lhasa (where he spent a month), before heading on to Nepal. He was followed by others who actually built a church in Lhasa. These included the Jesuit Father Ippolito Desideri, 1716–1721, who gained a deep knowledge of Tibetan culture, language and Buddhism, and various Capuchins in 1707–1711, 1716–1733 and 1741–1745, Christianity was used by some Tibetan monarchs and their courts and the Karmapa sect lamas to counterbalance the influence of the Gelugpa sect in the 17th century until in 1745 when all the missionaries were expelled at the lama's insistence.

A: Who crossed Nepal before heading to Tibet in 1661?
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Q: Passage: Charleston has one official sister city, Spoleto, Umbria, Italy. The relationship between the two cities began when Pulitzer Prize-winning Italian composer Gian Carlo Menotti selected Charleston as the city to host the American version of Spoleto's annual Festival of Two Worlds. "Looking for a city that would provide the charm of Spoleto, as well as its wealth of theaters, churches, and other performance spaces, they selected Charleston, South Carolina, as the ideal location. The historic city provided a perfect fit: intimate enough that the Festival would captivate the entire city, yet cosmopolitan enough to provide an enthusiastic audience and robust infrastructure."

A:
What is the name of Charleston's brother city?
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