Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Passage: The French and Indian War (1754–1763) was the North American theater of the worldwide Seven Years' War. The war was fought between the colonies of British America and New France, with both sides supported by military units from their parent countries of Great Britain and France, as well as Native American allies. At the start of the war, the French North American colonies had a population of roughly 60,000 European settlers, compared with 2 million in the British North American colonies. The outnumbered French particularly depended on the Indians. Long in conflict, the metropole nations declared war on each other in 1756, escalating the war from a regional affair into an intercontinental conflict.
Solution: When was the French and Indian War?
Reason: This question is based on the following sentence in the passage- The French and Indian War (1754–1763) was the North American theater of the worldwide Seven Years' War. It is a common convention to write (start year-end year) beside a historical event to understand when the event happened. You can ask questions like this one about dates, years, other numerals, persons, locations, noun phrases, verb phrases, adjectives, clauses etc. which exist in the paragraph.

Now, solve this instance: Providing 25% of Namibia's revenue, mining is the single most important contributor to the economy. Namibia is the fourth largest exporter of non-fuel minerals in Africa and the world's fourth largest producer of uranium. There has been significant investment in uranium mining and Namibia is set to become the largest exporter of uranium by 2015. Rich alluvial diamond deposits make Namibia a primary source for gem-quality diamonds. While Namibia is known predominantly for its gem diamond and uranium deposits, a number of other minerals are extracted industrially such as lead, tungsten, gold, tin, fluorspar, manganese, marble, copper and zinc. There are offshore gas deposits in the Atlantic Ocean that are planned to be extracted in the future. According to "The Diamond Investigation", a book about the global diamond market, from 1978, De Beers, the largest diamond company, bought most of the Namibian diamonds, and would continue to do so, because "whatever government eventually comes to power they will need this revenue to survive".
Student:
How much revenue does mining provide Namibia?