Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
The North American Environmental Atlas, produced by the Commission for Environmental Cooperation, a NAFTA agency composed of the geographical agencies of the Mexican, American, and Canadian governments uses the "Great Plains" as an ecoregion synonymous with predominant prairies and grasslands rather than as physiographic region defined by topography. The Great Plains ecoregion includes five sub-regions: Temperate Prairies, West-Central Semi-Arid Prairies, South-Central Semi-Arid Prairies, Texas Louisiana Coastal Plains, and Tamaulipus-Texas Semi-Arid Plain, which overlap or expand upon other Great Plains designations.
Between the Canadian, American, and Mexican portions of the Great Plains in which area does most of it lie?
A: unanswerable

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Indira Gandhi International Airport, situated to the southwest of Delhi, is the main gateway for the city's domestic and international civilian air traffic. In 2012-13, the airport was used by more than 35 million passengers, making it one of the busiest airports in South Asia. Terminal 3, which cost ₹96.8 billion (US$1.4 billion) to construct between 2007 and 2010, handles an additional 37 million passengers annually.
How many passengers use Terminal 3 of Indira Gandhi Airport each year?
A: 37 million

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Whereas Greg had limited his illustrative examples to English Renaissance drama, where his expertise lay, Bowers argued that the rationale was "the most workable editorial principle yet contrived to produce a critical text that is authoritative in the maximum of its details whether the author be Shakespeare, Dryden, Fielding, Nathaniel Hawthorne, or Stephen Crane. The principle is sound without regard for the literary period." For works where an author's manuscript survived – a case Greg had not considered – Bowers concluded that the manuscript should generally serve as copy-text. Citing the example of Nathaniel Hawthorne, he noted:
Greg was a novice in which period of drama?
A: unanswerable

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Simultaneous videoconferencing among three or more remote points is possible by means of a Multipoint Control Unit (MCU). This is a bridge that interconnects calls from several sources (in a similar way to the audio conference call). All parties call the MCU, or the MCU can also call the parties which are going to participate, in sequence. There are MCU bridges for IP and ISDN-based videoconferencing. There are MCUs which are pure software, and others which are a combination of hardware and software. An MCU is characterised according to the number of simultaneous calls it can handle, its ability to conduct transposing of data rates and protocols, and features such as Continuous Presence, in which multiple parties can be seen on-screen at once. MCUs can be stand-alone hardware devices, or they can be embedded into dedicated videoconferencing units.
In what way can an MCU be characterized?
A:
the number of simultaneous calls it can handle