instruction:
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.
question:
Passage: The service started on 1 September 1993 based on the idea from the then chief executive officer, Sam Chisholm and Rupert Murdoch, of converting the company business strategy to an entirely fee-based concept. The new package included four channels formerly available free-to-air, broadcasting on Astra's satellites, as well as introducing new channels. The service continued until the closure of BSkyB's analogue service on 27 September 2001, due to the launch and expansion of the Sky Digital platform. Some of the channels did broadcast either in the clear or soft encrypted (whereby a Videocrypt decoder was required to decode, without a subscription card) prior to their addition to the Sky Multichannels package. Within two months of the launch, BSkyB gained 400,000 new subscribers, with the majority taking at least one premium channel as well, which helped BSkyB reach 3.5 million households by mid-1994. Michael Grade criticized the operations in front of the Select Committee on National Heritage, mainly for the lack of original programming on many of the new channels.
answer:
What platform helped BSkyB to avoid ending their analogue service?

question:
Passage: The name of the metal was probably first documented by Paracelsus, a Swiss-born German alchemist, who referred to the metal as "zincum" or "zinken" in his book Liber Mineralium II, in the 16th century. The word is probably derived from the German zinke, and supposedly meant "tooth-like, pointed or jagged" (metallic zinc crystals have a needle-like appearance). Zink could also imply "tin-like" because of its relation to German zinn meaning tin. Yet another possibility is that the word is derived from the Persian word seng meaning stone. The metal was also called Indian tin, tutanego, calamine, and spinter.
answer:
Who is attributed as the only person to document zinc?

question:
Passage: Capacitors, especially ceramic capacitors, and older designs such as paper capacitors, can absorb sound waves resulting in a microphonic effect. Vibration moves the plates, causing the capacitance to vary, in turn inducing AC current. Some dielectrics also generate piezoelectricity. The resulting interference is especially problematic in audio applications, potentially causing feedback or unintended recording. In the reverse microphonic effect, the varying electric field between the capacitor plates exerts a physical force, moving them as a speaker. This can generate audible sound, but drains energy and stresses the dielectric and the electrolyte, if any.
answer:
What is the effect called when capacitors don't absorb sound waves?