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: There has, however, been interest among railroad operators in returning to DC use at higher voltages than previously used. At the same voltage, DC often has less loss than AC, and for this reason high-voltage direct current is already used on some bulk power transmission lines. DC avoids the electromagnetic radiation inherent with AC, and on a railway this also reduces interference with signalling and communications and mitigates hypothetical EMF risks. DC also avoids the power factor problems of AC. Of particular interest to railroading is that DC can supply constant power with a single ungrounded wire. Constant power with AC requires three-phase transmission with at least two ungrounded wires. Another important consideration is that mains-frequency 3-phase AC must be carefully planned to avoid unbalanced phase loads. Parts of the system are supplied from different phases on the assumption that the total loads of the 3 phases will even out. At the phase break points between regions supplied from different phases, long insulated supply breaks are required to avoid them being shorted by rolling stock using more than one pantograph at a time. A few railroads have tried 3-phase but its substantial complexity has made single-phase standard practice despite the interruption in power flow that occurs twice every cycle. An experimental 6 kV DC railway was built in the Soviet Union.

Ex Output:
Railroad operators have shown little interest in returning to what?

Ex Input:
Passage: Code points in the range U+D800U+DBFF (1,024 code points) are known as high-surrogate code points, and code points in the range U+DC00U+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+0000U+D7FF and U+E000U+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.

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

Ex Input:
Passage: Throughout history there have been a series of lingua francas in the area to allow for better communication. The dialects spoken in Hangzhou, Shaoxing, and Ningbo have taken on this role historically. Since the founding of the People's Republic of China in 1949, Mandarin, which is not mutually intelligible with any of the local dialects, has been promoted as the standard language of communication throughout China. As a result, most of the population now can, to some degree, speak and comprehend Mandarin and can code-switch when necessary. A majority of the population educated since 1978 can speak Mandarin. Urban residents tend to be more fluent in Mandarin than rural people. Nevertheless, a Zhejiang accent is detectable in almost everyone from the area communicating in Mandarin, and the home dialect remains an important part of the everyday lives and cultural identities of most Zhejiang residents.

Ex Output:
When was the People's Republic of China defunct?