This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Example Input: After 1870, the new railroads across the Plains brought hunters who killed off almost all the bison for their hides. The railroads offered attractive packages of land and transportation to European farmers, who rushed to settle the land. They (and Americans as well) also took advantage of the homestead laws to obtain free farms. Land speculators and local boosters identified many potential towns, and those reached by the railroad had a chance, while the others became ghost towns. In Kansas, for example, nearly 5000 towns were mapped out, but by 1970 only 617 were actually operating. In the mid-20th century, closeness to an interstate exchange determined whether a town would flourish or struggle for business.
Example Output: after about what year did railroads bring hunters to the great plains?

Example Input: 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.
Example Output: What ingredient makes glass colorful?

Example Input: Private schools generally prefer to be called independent schools, because of their freedom to operate outside of government and local government control. Some of these are also known as public schools. Preparatory schools in the UK prepare pupils aged up to 13 years old to enter public schools. The name "public school" is based on the fact that the schools were open to pupils from anywhere, and not merely to those from a certain locality, and of any religion or occupation. According to The Good Schools Guide approximately 9 per cent of children being educated in the UK are doing so at fee-paying schools at GSCE level and 13 per cent at A-level.[citation needed] Many independent schools are single-sex (though this is becoming less common). Fees range from under £3,000 to £21,000 and above per year for day pupils, rising to £27,000+ per year for boarders. For details in Scotland, see "Meeting the Cost".
Example Output:
Up to what age do students in the United Kingdom attend preparatory schools?