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.
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Question: Passage: Code points in the range U+D800–U+DBFF (1,024 code points) are known as high-surrogate code points, and code points in the range U+DC00–U+DFFF (1,024 code points) are known as low-surrogate code points. A high-surrogate code point (also known as a leading surrogate) followed by a low-surrogate code point (also known as a trailing surrogate) together form a surrogate pair used in UTF-16 to represent 1,048,576 code points outside BMP. High and low surrogate code points are not valid by themselves. Thus the range of code points that are available for use as characters is U+0000–U+D7FF and U+E000–U+10FFFF (1,112,064 code points). The value of these code points (i.e., excluding surrogates) is sometimes referred to as the character's scalar value.

Answer: What is a low-surrogate followed by a high-surrogate called?


Question: Passage: The Raleigh Parks and Recreation Department offers a wide variety of leisure opportunities at more than 150 sites throughout the city, which include: 8,100 acres (33 km2) of park land, 78 miles (126 km) of greenway, 22 community centers, a BMX championship-caliber race track, 112 tennis courts among 25 locations, 5 public lakes, and 8 public aquatic facilities. The J. C. Raulston Arboretum, an 8-acre (32,000 m²) arboretum and botanical garden in west Raleigh administered by North Carolina State University, maintains a year-round collection that is open daily to the public without charge.

Answer: What has more than 200 sites throughout the city?


Question: Passage: BSkyB launched its HDTV service, Sky+ HD, on 22 May 2006. Prior to its launch, BSkyB claimed that 40,000 people had registered to receive the HD service. In the week before the launch, rumours started to surface that BSkyB was having supply issues with its set top box (STB) from manufacturer Thomson. On Thursday 18 May 2006, and continuing through the weekend before launch, people were reporting that BSkyB had either cancelled or rescheduled its installation. Finally, the BBC reported that 17,000 customers had yet to receive the service due to failed deliveries. On 31 March 2012, Sky announced the total number of homes with Sky+HD was 4,222,000.

Answer:
When did BSkyB fail launching it's HDTV service?