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.

Input: Consider Input: 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.

Output: By who was the sailing ships occupied?


Input: Consider Input: Passage: Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used for this purpose, and this is likely to remain one of their major uses until the price drops low enough to make signaling and illumination uses more widespread. Barcode scanners are the most common example of machine vision, and many low cost products use red LEDs instead of lasers. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons:

Output:  non-LEDs are often used for what type of systems?


Input: Consider Input: Passage: The history of a unified Tibet begins with the rule of Songtsän Gampo (604–650 CE), who united parts of the Yarlung River Valley and founded the Tibetan Empire. He also brought in many reforms, and Tibetan power spread rapidly, creating a large and powerful empire. It is traditionally considered that his first wife was the Princess of Nepal, Bhrikuti, and that she played a great role in the establishment of Buddhism in Tibet. In 640 he married Princess Wencheng, the niece of the powerful Chinese emperor Taizong of Tang China.


Output: Who ruled Tibet from 640-650 CE?