The problem: Answer a question about this article:
In November 2004, following a period of turmoil caused by the revelation that Shell had been overstating its oil reserves, it was announced that the Shell Group would move to a single capital structure, creating a new parent company to be named Royal Dutch Shell plc, with its primary listing on the London Stock Exchange, a secondary listing on the Amsterdam Stock Exchange, its headquarters and tax residency in The Hague, Netherlands and its registered office in London. The unification was completed on 20 July 2005 and the original owners delisted their companies from the respective exchanges. On 20 July 2005, the Shell Transport & Trading Company plc was delisted from the LSE, where as, Royal Dutch Petroleum Company from NYSE on 18 November 2005. The shares of the company were issued at a 60/40 advantage for the shareholders of Royal Dutch in line with the original ownership of the Shell Group.
On what exchange was the Shell Group's new parent company primarily listed?
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The answer: the London Stock Exchange

The problem: Answer a question about this article:
Most modern air defence systems are fairly mobile. Even the larger systems tend to be mounted on trailers and are designed to be fairly quickly broken down or set up. In the past, this was not always the case. Early missile systems were cumbersome and required much infrastructure; many could not be moved at all. With the diversification of air defence there has been much more emphasis on mobility. Most modern systems are usually either self-propelled (i.e. guns or missiles are mounted on a truck or tracked chassis) or easily towed. Even systems that consist of many components (transporter/erector/launchers, radars, command posts etc.) benefit from being mounted on a fleet of vehicles. In general, a fixed system can be identified, attacked and destroyed whereas a mobile system can show up in places where it is not expected. Soviet systems especially concentrate on mobility, after the lessons learnt in the Vietnam war between the USA and Vietnam. For more information on this part of the conflict, see SA-2 Guideline.
What are larger weapon systems usually mounted on?
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The answer: trailers

The problem: Answer a question about this article:
Longer works are often divided into self-contained pieces, called movements, often with contrasting characters or moods. For instance, symphonies written during the Classical period are usually divided into four movements: (1) an opening Allegro in sonata form, (2) a slow movement, (3) a minuet or scherzo, and (4) a final Allegro. These movements can then be further broken down into a hierarchy of smaller units: first sections, then periods, and finally phrases.
What are self-contained pieces in longer works called?
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The answer: movements

The problem: Answer a question about this article:
Everything in between the far south and the far north is savannah (insignificant tree cover, with grasses and flowers located between trees). Rainfall is more limited, to between 500 and 1,500 millimetres (20 and 60 in) per year. The savannah zone's three categories are Guinean forest-savanna mosaic, Sudan savannah, and Sahel savannah. Guinean forest-savanna mosaic is plains of tall grass interrupted by trees. Sudan savannah is similar but with shorter grasses and shorter trees. Sahel savannah consists of patches of grass and sand, found in the northeast. In the Sahel region, rain is less than 500 millimetres (20 in) per year and the Sahara Desert is encroaching. In the dry north-east corner of the country lies Lake Chad, which Nigeria shares with Niger, Chad and Cameroon.
Which desert is encroaching into northeastern Nigeria?
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The answer:
Sahara