Input: Software testing
As the number of possible tests for even simple software components is practically infinite, all software testing uses some strategy to select tests that are feasible for the available time and resources. As a result, software testing typically (but not exclusively) attempts to execute a program or application with the intent of finding software bugs (errors or other defects). The job of testing is an iterative process as when one bug is fixed, it can illuminate other, deeper bugs, or can even create new ones.

Why is it so difficult to locate bugs in software?
Output: tests for even simple software components is practically infinite


Input: Article: Since the armature windings of a direct-current or universal motor are moving through a magnetic field, they have a voltage induced in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (emf)". The voltage is proportional to the running speed of the motor. The back emf of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back emf results, and more current is drawn from the supply. This increased current provides the additional torque to balance the new load.

Now answer this question: Voltage opposing the motor supply voltage is called what?

Output: back electromotive force


Article: There are many important organozinc compounds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions. Among important applications is the Frankland-Duppa Reaction in which an oxalate ester(ROCOCOOR) reacts with an alkyl halide R'X, zinc and hydrochloric acid to the α-hydroxycarboxylic esters RR'COHCOOR, the Reformatskii reaction which converts α-halo-esters and aldehydes to β-hydroxy-esters, the Simmons–Smith reaction in which the carbenoid (iodomethyl)zinc iodide reacts with alkene(or alkyne) and converts them to cyclopropane, the Addition reaction of organozinc compounds to carbonyl compounds. The Barbier reaction (1899) is the zinc equivalent of the magnesium Grignard reaction and is better of the two. In presence of just about any water the formation of the organomagnesium halide will fail, whereas the Barbier reaction can even take place in water. On the downside organozincs are much less nucleophilic than Grignards, are expensive and difficult to handle. Commercially available diorganozinc compounds are dimethylzinc, diethylzinc and diphenylzinc. In one study the active organozinc compound is obtained from much cheaper organobromine precursors:

Question: What is the zinc equivalent of the Grinard reaction?
Ans: The Barbier reaction


Here is a question about this article: The most important existing communal shelters were the London Underground stations. Although many civilians had used them as such during the First World War, the government in 1939 refused to allow the stations to be used as shelters so as not to interfere with commuter and troop travel, and the fears that occupants might refuse to leave. Underground officials were ordered to lock station entrances during raids; but by the second week of heavy bombing the government relented and ordered the stations to be opened. Each day orderly lines of people queued until 4 pm, when they were allowed to enter the stations. In mid-September 1940 about 150,000 a night slept in the Underground, although by the winter and spring months the numbers had declined to 100,000 or less. Noises of battle were muffled and sleep was easier in the deepest stations, but many were killed from direct hits on several stations.
What is the answer to this question: Why were many killed in Underground Stations?
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So... direct hits


The problem: Answer a question about this article:
In the Roman era, copper was principally mined on Cyprus, the origin of the name of the metal from aes сyprium (metal of Cyprus), later corrupted to сuprum, from which the words copper (English), cuivre (French), Koper (Dutch) and Kupfer (German) are all derived. Its compounds are commonly encountered as copper(II) salts, which often impart blue or green colors to minerals such as azurite, malachite and turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina). Decorative art prominently features copper, both by itself and in the form of pigments.
What is the name of the color pigment on building structures that are made using copper.
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The answer: green verdigris


The problem: Answer a question about this article:
Ibn Sina subsequently settled at Rey, in the vicinity of modern Tehran, the home town of Rhazes; where Majd Addaula, a son of the last Buwayhid emir, was nominal ruler under the regency of his mother (Seyyedeh Khatun). About thirty of Ibn Sina's shorter works are said to have been composed in Rey. Constant feuds which raged between the regent and her second son, Shams al-Daula, however, compelled the scholar to quit the place. After a brief sojourn at Qazvin he passed southwards to Hamadãn where Shams al-Daula, another Buwayhid emir, had established himself. At first, Ibn Sina entered into the service of a high-born lady; but the emir, hearing of his arrival, called him in as medical attendant, and sent him back with presents to his dwelling. Ibn Sina was even raised to the office of vizier. The emir decreed that he should be banished from the country. Ibn Sina, however, remained hidden for forty days in sheikh Ahmed Fadhel's house, until a fresh attack of illness induced the emir to restore him to his post. Even during this perturbed time, Ibn Sina persevered with his studies and teaching. Every evening, extracts from his great works, the Canon and the Sanatio, were dictated and explained to his pupils. On the death of the emir, Ibn Sina ceased to be vizier and hid himself in the house of an apothecary, where, with intense assiduity, he continued the composition of his works.
What modern city of today was Rey in the vicinity of?
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The answer:
Tehran