Problem: Please answer a question about the following article about Gene:
Due to the chemical composition of the pentose residues of the bases, DNA strands have directionality. One end of a DNA polymer contains an exposed hydroxyl group on the deoxyribose; this is known as the 3' end of the molecule. The other end contains an exposed phosphate group; this is the 5' end. The two strands of a double-helix run in opposite directions. Nucleic acid synthesis, including DNA replication and transcription occurs in the 5'→3' direction, because new nucleotides are added via a dehydration reaction that uses the exposed 3' hydroxyl as a nucleophile.:27.2
What causes the directionality of DNA strands?
A: the chemical composition of the pentose residues of the bases
Problem: Please answer a question about the following article about Somerset:
The county has a long tradition of supplying freestone and building stone. Quarries at Doulting supplied freestone used in the construction of Wells Cathedral. Bath stone is also widely used. Ralph Allen promoted its use in the early 18th century, as did Hans Price in the 19th century, but it was used long before then. It was mined underground at Combe Down and Bathampton Down Mines, and as a result of cutting the Box Tunnel, at locations in Wiltshire such as Box. Bath stone is still used on a reduced scale today, but more often as a cladding rather than a structural material. Further south, Hamstone is the colloquial name given to stone from Ham Hill, which is also widely used in the construction industry. Blue Lias has been used locally as a building stone and as a raw material for lime mortar and Portland cement. Until the 1960s, Puriton had Blue Lias stone quarries, as did several other Polden villages. Its quarries also supplied a cement factory at Dunball, adjacent to the King's Sedgemoor Drain. Its derelict, early 20th century remains, was removed when the M5 motorway was constructed in the mid-1970s. Since the 1920s, the county has supplied aggregates. Foster Yeoman is Europe's large supplier of limestone aggregates, with quarries at Merehead Quarry. It has a dedicated railway operation, Mendip Rail, which is used to transport aggregates by rail from a group of Mendip quarries.
What type of stone was supplied in the county 
A: supplying freestone and building stone
Problem: Please answer a question about the following article about Mosaic:
A striking technical innovation of the Komnenian period was the production of very precious, miniature mosaic icons. In these icons the small tesserae (with sides of 1 mm or less) were set on wax or resin on a wooden panel. These products of extraordinary craftmanship were intended for private devotion. The Louvre Transfiguration is a very fine example from the late 12th century. The miniature mosaic of Christ in the Museo Nazionale at Florence illustrates the more gentle, humanistic conception of Christ which appeared in the 12th century.
What was the intended purpose of the miniature mosaic icons?
A: private devotion
Problem: Please answer a question about the following article about Frédéric Chopin:
Polish composers of the following generation included virtuosi such as Moritz Moszkowski, but, in the opinion of J. Barrie Jones, his "one worthy successor" among his compatriots was Karol Szymanowski (1882–1937). Edvard Grieg, Antonín Dvořák, Isaac Albéniz, Pyotr Ilyich Tchaikovsky and Sergei Rachmaninoff, among others, are regarded by critics as having been influenced by Chopin's use of national modes and idioms. Alexander Scriabin was devoted to the music of Chopin, and his early published works include nineteen mazurkas, as well as numerous études and preludes; his teacher Nikolai Zverev drilled him in Chopin's works to improve his virtuosity as a performer. In the 20th century, composers who paid homage to (or in some cases parodied) the music of Chopin included George Crumb, Bohuslav Martinů, Darius Milhaud, Igor Stravinsky and Heitor Villa-Lobos.
Who was Alexander Scriabin's teacher?
A:
Nikolai Zverev