input question: Extract the answer to the question from the following context. Question: What is the organometallic precursor for the Grignard reaction? Context: 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 -hydroxycarboxylic esters RR'COHCOOR, the Reformatskii reaction which converts -halo-esters and aldehydes to -hydroxy-esters, the SimmonsSmith 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:???
output answer: organomagnesium

Extract the answer to the question from the following context. Question: What was an initial shortfall of digital media? Context: Similar to the CD versus LP sound quality debates common in the audiophile community, some videophiles argue that LaserDisc maintains a "smoother", more "film-like", natural image while DVD still looks slightly more artificial. Early DVD demo discs often had compression or encoding problems, lending additional support to such claims at the time. However, the video signal-to-noise ratio and bandwidth of LaserDisc are substantially less than that of DVDs, making DVDs appear sharper and clearer to most viewers.
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Answer: compression or encoding problems

Q: Extract the answer to the question from the following context. Question: The middle way may also be known as what path? Context: According to Vetter, the description of the Buddhist path may initially have been as simple as the term "the middle way". In time, this short description was elaborated, resulting in the description of the eightfold path.
A: eightfold

Question: Extract the answer to the question from the following context. Question: What goes to the geometrical building? Context: Inner and outer vestibules lead to the octagonal chapter house, which is of exceptional architectural purity. It is built in a Geometrical Gothic style with an octagonal crypt below. A pier of eight shafts carries the vaulted ceiling. To the sides are blind arcading, remains of 14th-century paintings and numerous stone benches above which are innovatory large 4-light quatre-foiled windows. These are virtually contemporary with the Sainte-Chapelle, Paris.
Answer: Inner and outer vestibules

[Q]: Extract the answer to the question from the following context. Question: what group was mentioned last? Context: After a difficult winter, most of the Denny Party relocated across Elliott Bay and claimed land a second time at the site of present-day Pioneer Square. Charles Terry and John Low remained at the original landing location and reestablished their old land claim and called it "New York", but renamed "New York Alki" in April 1853, from a Chinook word meaning, roughly, "by and by" or "someday". For the next few years, New York Alki and Duwamps competed for dominance, but in time Alki was abandoned and its residents moved across the bay to join the rest of the settlers.
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[A]: settlers

Problem: Given the question: Extract the answer to the question from the following context. Question: What happened before the last naval battle took place? Context: Because neither Korea had a significant navy, the Korean War featured few naval battles. A skirmish between North Korea and the UN Command occurred on 2 July 1950; the U.S. Navy cruiser USS Juneau, the Royal Navy cruiser HMS Jamaica, and the frigate HMS Black Swan fought four North Korean torpedo boats and two mortar gunboats, and sank them. USS Juneau later sank several ammunition ships that had been present. The last sea battle of the Korean War occurred at Inchon, days before the Battle of Incheon; the ROK ship PC-703 sank a North Korean mine layer in the Battle of Haeju Island, near Inchon. Three other supply ships were sunk by PC-703 two days later in the Yellow Sea. Thereafter, vessels from the UN nations held undisputed control of the sea about Korea. The gun ships were used in shore bombardment, while the aircraft carriers provided air support to the ground forces.
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The answer is:
the ROK ship PC-703 sank a North Korean mine layer in the Battle of Haeju Island