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: The islands were occupied by a garrison of British Marines and a civilian population was gradually built up. Whalers also set up on the islands as a base for operations in the Southern Atlantic. However, the opening of the Suez Canal in 1869, together with the gradual move from sailing ships to coal-fired steam ships, increased the isolation of the islands, as they were no longer needed as a stopping port or for shelter for journeys from Europe to East Asia.

Answer: By who was the sailing ships occupied?


Question: Passage: The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. The document is known colloquially as the Red Book CD-DA after the colour of its cover. The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel. Four-channel sound was to be an allowable option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; thus, mono source material is usually presented as two identical channels in a standard Red Book stereo track (i.e., mirrored mono); an MP3 CD, however, can have audio file formats with mono sound.

Answer: What was the sampling rate for the four-channel sound?


Question: Passage: The origins of al-Qaeda can be traced to the Soviet war in Afghanistan (December 1979 – February 1989). The United States, United Kingdom, Saudi Arabia, Pakistan, and the People's Republic of China supported the Islamist Afghan mujahadeen guerillas against the military forces of the Soviet Union and the Democratic Republic of Afghanistan. A small number of "Afghan Arab" volunteers joined the fight against the Soviets, including Osama bin Laden, but there is no evidence they received any external assistance. In May 1996 the group World Islamic Front for Jihad Against Jews and Crusaders (WIFJAJC), sponsored by bin Laden (and later re-formed as al-Qaeda), started forming a large base of operations in Afghanistan, where the Islamist extremist regime of the Taliban had seized power earlier in the year. In February 1998, Osama bin Laden signed a fatwā, as head of al-Qaeda, declaring war on the West and Israel, later in May of that same year al-Qaeda released a video declaring war on the U.S. and the West.

Answer:
What took place from February 1979 to December 1989?