Problem: Solar energy:

A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.

Why is the use of solar balloons typically limited to the toy market?
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A: the surface-area to payload-weight ratio is relatively high

Problem: Most graduate immunology schools follow the AAI courses immunology which are offered throughout numerous schools in the United States. For example, in New York State, there are several universities that offer the AAI courses immunology: Albany Medical College, Cornell University, Icahn School of Medicine at Mount Sinai, New York University Langone Medical Center, University at Albany (SUNY), University at Buffalo (SUNY), University of Rochester Medical Center and Upstate Medical University (SUNY). The AAI immunology courses include an Introductory Course and an Advance Course. The Introductory Course is a course that gives students an overview of the basics of immunology.
Most graduate schools specializing in immunology follow what organization's parameters?
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Answer: AAI courses

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Avicenna's consideration of the essence-attributes question may be elucidated in terms of his ontological analysis of the modalities of being; namely impossibility, contingency, and necessity. Avicenna argued that the impossible being is that which cannot exist, while the contingent in itself (mumkin bi-dhatihi) has the potentiality to be or not to be without entailing a contradiction. When actualized, the contingent becomes a 'necessary existent due to what is other than itself' (wajib al-wujud bi-ghayrihi). Thus, contingency-in-itself is potential beingness that could eventually be actualized by an external cause other than itself. The metaphysical structures of necessity and contingency are different. Necessary being due to itself (wajib al-wujud bi-dhatihi) is true in itself, while the contingent being is 'false in itself' and 'true due to something else other than itself'. The necessary is the source of its own being without borrowed existence. It is what always exists.
According to Avicenna, what could eventually be actualized by an external cause?
A: contingency-in-itself

Context and question: CJON-DT, known on air as "NTV", is an independent station. The station sublicenses entertainment programming from Global and news programming from CTV and Global, rather than purchasing primary broadcast rights. Rogers Cable has its provincial headquarters in St. John's, and their community channel Rogers TV airs local shows such as Out of the Fog and One Chef One Critic. CBC has its Newfoundland and Labrador headquarters in the city and their television station CBNT-DT broadcasts from University Avenue.
What public radio station serves the city?
Answer: unanswerable

Question: Borders Books, started in Ann Arbor, was opened by brothers Tom and Louis Borders in 1971 with a stock of used books. The Borders chain was based in the city, as was its flagship store until it closed in September 2011. Domino's Pizza's headquarters is near Ann Arbor on Domino's Farms, a 271-acre (110 ha) Frank Lloyd Wright-inspired complex just northeast of the city. Another Ann Arbor-based company is Zingerman's Delicatessen, which serves sandwiches and has developed businesses under a variety of brand names. Zingerman's has grown into a family of companies which offers a variety of products (bake shop, mail order, creamery, coffee) and services (business education). Flint Ink Corp., another Ann Arbor-based company, was the world's largest privately held ink manufacturer until it was acquired by Stuttgart-based XSYS Print Solutions in October 2005. Avfuel, a global supplier of aviation fuels and services, is also headquartered in Ann Arbor. Aastrom Biosciences, a publicly traded company that develops stem cell treatments for cardiovascular diseases, is headquartered in Ann Arbor.
Is there an answer to this question: What bookstore was started by Tom and Lois Borders?

Answer: unanswerable

As one of their first acts after end of the War of the Castilian Succession in 1479, Ferdinand and Isabella established the centrally organized and efficient Holy Brotherhood (Santa Hermandad) as a national police force. They adapted an existing brotherhood to the purpose of a general police acting under officials appointed by themselves, and endowed with great powers of summary jurisdiction even in capital cases. The original brotherhoods continued to serve as modest local police-units until their final suppression in 1835.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): When did Spain suppress local police units?
Ah, so..
1835