Problem: Exhibition game:

The Major League Baseball's preseason is also known as spring training. All MLB teams maintain a spring-training base in Arizona or Florida. The teams in Arizona make up the Cactus League, while the teams in Florida play in the Grapefruit League. Each team plays about 30 preseason games against other MLB teams. They may also play exhibitions against a local college team or a minor-league team from their farm system. Some days feature the team playing two games with two different rosters evenly divided up, which are known as "split-squad" games.

What is the minor league baseball preseason known as?
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A: unanswerable


Problem: The World Bank has sponsored a project to curb air pollution through public transport improvements and the Mexican government has started shutting down polluting factories. They have phased out diesel buses and mandated new emission controls on new cars; since 1993 all new cars must be fitted with a catalytic converter, which reduces the emissions released. Trucks must use only liquefied petroleum gas (LPG). Also construction of an underground rail system was begun in 1968 in order to help curb air pollution problems and alleviate traffic congestion. Today it has over 201 km (125 mi) of track and carries over 5 million people every day. Fees are kept low to encourage use of the system and during rush hours the crush is so great, that authorities have reserved a special carriage specifically for women. Due to these initiatives and others, the air quality in Mexico City has begun to improve, with the air becoming cleaner since 1991, when the air quality was declared to be a public health risk for 355 days of the year.[citation needed]
How many days of the year in 1991 was the air pollution a serious health risk?
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Answer: 355


Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Constantius, ordered Liberius into exile in 356 giving him, then, three days to comply. He was ordered into banishment to Beroea, in Thrace; Beroea (Thrace). He sent expensive presents, too, if he were to accept the Arian position but were refused. He sent him, indeed, five hundred pieces of gold "to bear his charges" but Liberius refused them, saying, he might bestow them on his flatters; as he did also a like present from the empress, bidding the messenger learn to believe in Christ, and not to persecute the Church of God. Attempts were made to leave the presents in The Church, but Liberius threw them out. Constantius hereupon sent for him under a strict guard to Milan, where, in a conference recorded by Theodoret, he boldly told Constantius that Athanasius had been acquitted at Sardica, and his enemies proved calumniators (see: "calumny") and impostors, and that it was unjust to condemn a person who could not be legally convicted of any crime. The emperor was reduced to silence on every article, but being the more out of patience, ordered him into banishment. Liberius went into exile. Constantius, after two years went to Rome to celebrate the twentieth year of his reign. The ladies joined in a petition to him that he would restore Liberius. He assented, upon condition that he should comply with the bishops, then, at court. He subscribed the condemnation of Athanasius, and a confession or creed which had been framed by the Arians at Sirmium. And he no sooner had recovered his see that he declared himself for the Creed of Niceae, as Theodoret testifies. (Theodoret, Hist. lib. ii. c. 17.). The Emperor knew what he wanted people to believe. So did the bishops at his court. Athanasius stuck by the orthodox creed. Constantius was an avowed Arian, became sole ruler in 350, at the death of his brother, Constans.
How much warning was Liberius given before his freedom?
A: unanswerable


Context and question: It was not long until Apple released their first portable computer, the Macintosh Portable in 1989. Although due to considerable design issues, it was soon replaced in 1991 with the first of the PowerBook line: the PowerBook 100, a miniaturized portable; the 16 MHz 68030 PowerBook 140; and the 25 MHz 68030 PowerBook 170. They were the first portable computers with the keyboard behind a palm rest and a built-in pointing device (a trackball) in front of the keyboard. The 1993 PowerBook 165c was Apple's first portable computer to feature a color screen, displaying 256 colors with 640 x 400-pixel resolution. The second generation of PowerBooks, the 68040-equipped 500 series, introduced trackpads, integrated stereo speakers, and built-in Ethernet to the laptop form factor in 1994.
What replaced the Macintosh Portable in 1992?
Answer: unanswerable


Question: Some of the best examples of later Islamic mosaics were produced in Moorish Spain. The golden mosaics in the mihrab and the central dome of the Great Mosque in Corduba have a decidedly Byzantine character. They were made between 965 and 970 by local craftsmen, supervised by a master mosaicist from Constantinople, who was sent by the Byzantine Emperor to the Umayyad Caliph of Spain. The decoration is composed of colorful floral arabesques and wide bands of Arab calligraphy. The mosaics were purported to evoke the glamour of the Great Mosque in Damascus, which was lost for the Umayyad family.
Is there an answer to this question: Who sent the master mosaicist to Spain?

Answer: the Byzantine Emperor


Question: One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates can not be applied ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even clearly infectious diseases do not meet the infectious criteria. For example, Treponema pallidum, the causative spirochete of syphilis, cannot be cultured in vitro - however the organism can be cultured in rabbit testes. It is less clear that a pure culture comes from an animal source serving as host than it is when derived from microbes derived from plate culture. Epidemiology is another important tool used to study disease in a population. For infectious diseases it helps to determine if a disease outbreak is sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic).
Is there an answer to this question: Why can't Koch's postulates be applied ethically for many human diseases?

Answer:
because they require experimental infection of a healthy individual