Input: Read this: With the Conference of Berlin of 1884, Portuguese Africa territories had their borders formally established on request of Portugal in order to protect the centuries-long Portuguese interests in the continent from rivalries enticed by the Scramble for Africa. Portuguese Africa's cities and towns like Nova Lisboa, Sá da Bandeira, Silva Porto, Malanje, Tete, Vila Junqueiro, Vila Pery and Vila Cabral were founded or redeveloped inland during this period and beyond. New coastal towns like Beira, Moçâmedes, Lobito, João Belo, Nacala and Porto Amélia were also founded. Even before the turn of the 20th century, railway tracks as the Benguela railway in Angola, and the Beira railway in Mozambique, started to be built to link coastal areas and selected inland regions.
Question: When was the Conference of Berlin held?

Output: 1884


Input: Read this: Many applications of silicate glasses derive from their optical transparency, which gives rise to one of silicate glasses' primary uses as window panes. Glass will transmit, reflect and refract light; these qualities can be enhanced by cutting and polishing to make optical lenses, prisms, fine glassware, and optical fibers for high speed data transmission by light. Glass can be colored by adding metallic salts, and can also be painted and printed with vitreous enamels. These qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures. Because glass can be formed or molded into any shape, and also because it is a sterile product, it has been traditionally used for vessels: bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also been used for paperweights, marbles, and beads. When extruded as glass fiber and matted as glass wool in a way to trap air, it becomes a thermal insulating material, and when these glass fibers are embedded into an organic polymer plastic, they are a key structural reinforcement part of the composite material fiberglass. Some objects historically were so commonly made of silicate glass that they are simply called by the name of the material, such as drinking glasses and reading glasses.
Question: What in combination with glass fibers is used to make glass wool?

Output: unanswerable


Input: Read this: Timber was the chief building material during the Han dynasty; it was used to build palace halls, multi-story residential towers and halls and single-story houses. Because wood decays rapidly, the only remaining evidence of Han wooden architecture is a collection of scattered ceramic roof tiles. The oldest surviving wooden halls in China date to the Tang dynasty (618–907 AD). Architectural historian Robert L. Thorp points out the scarcity of Han-era archaeological remains, and claims that often unreliable Han-era literary and artistic sources are used by historians for clues about lost Han architecture.
Question: What was the primary component of a palace hall during the Han dynasty?

Output: Timber


Input: Read this: By 1975 the majority of local authorities in England and Wales had abandoned the 11-plus examination and moved to a comprehensive system. Over that 10-year period many secondary modern schools and grammar schools were amalgamated to form large neighbourhood comprehensives, whilst a number of new schools were built to accommodate a growing school population. By the mid-1970s the system had been almost fully implemented, with virtually no secondary modern schools remaining. Many grammar schools were either closed or changed to comprehensive status. Some local authorities, including Sandwell and Dudley in the West Midlands, changed all of its state secondary schools to comprehensive schools during the 1970s.
Question: What are two locations in which all secondary schools were converted to comprehensives in the '70s?

Output:
Sandwell and Dudley