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.

Example Input: Passage: The South Saharan steppe and woodlands ecoregion is a narrow band running east and west between the hyper-arid Sahara and the Sahel savannas to the south. Movements of the equatorial Intertropical Convergence Zone (ITCZ) bring summer rains during July and August which average 100 to 200 mm (3.9 to 7.9 in) but vary greatly from year to year. These rains sustain summer pastures of grasses and herbs, with dry woodlands and shrublands along seasonal watercourses. This ecoregion covers 1,101,700 km2 (425,400 mi2) in Algeria, Chad, Mali, Mauritania, and Sudan.
Example Output: what ecoregion runs north and south in a norrow band?

Example Input: Passage: Other types of lossy compressors, such as the linear predictive coding (LPC) used with speech, are source-based coders. These coders use a model of the sound's generator (such as the human vocal tract with LPC) to whiten the audio signal (i.e., flatten its spectrum) before quantization. LPC may be thought of as a basic perceptual coding technique: reconstruction of an audio signal using a linear predictor shapes the coder's quantization noise into the spectrum of the target signal, partially masking it.
Example Output: What is thought of as a basic signal coding technique?

Example Input: Passage: Believed to be a stowaway on a U.S. military transport near the end of World War II, the brown tree snake (Boiga irregularis) was accidentally introduced to Guam, that previously had no native species of snake. It nearly eliminated the native bird population. The problem was exacerbated because the reptile has no natural predators on the island. The brown tree snake, known locally as the kulebla, is native to northern and eastern coasts of Australia, Papua New Guinea, and the Solomon Islands. While slightly venomous, the snake is relatively harmless to human beings. Although some studies have suggested a high density of these serpents on Guam, residents rarely see the nocturnal creatures. The United States Department of Agriculture has trained detector dogs to keep the snakes out of the island's cargo flow. The United States Geological Survey also has dogs capable of detecting snakes in forested environments around the region's islands.
Example Output:
How many native species of birds did Guam have prior to World War II?