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The Ordovician Period started at a major extinction event called the Cambrian-Ordovician extinction events some time about 485.4 1.9 Ma. During the Ordovician the southern continents were collected into a single continent called Gondwana. Gondwana started the period in the equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician the continents Laurentia, Siberia and Baltica were still independent continents (since the break-up of the supercontinent Pannotia earlier), but Baltica began to move toward Laurentia later in the period, causing the Iapetus Ocean to shrink between them. Also, Avalonia broke free from Gondwana and began to head north toward Laurentia. The Rheic Ocean was formed as a result of this. By the end of the period, Gondwana had neared or approached the pole and was largely glaciated.
What was the name of the period that ended with a major extinction event?
A: unanswerable

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Tuberculosis is the second-most common cause of death from infectious disease (after those due to HIV/AIDS). The total number of tuberculosis cases has been decreasing since 2005, while new cases have decreased since 2002. China has achieved particularly dramatic progress, with about an 80% reduction in its TB mortality rate between 1990 and 2010. The number of new cases has declined by 17% between 20042014. Tuberculosis is more common in developing countries; about 80% of the population in many Asian and African countries test positive in tuberculin tests, while only 510% of the US population test positive. Hopes of totally controlling the disease have been dramatically dampened because of a number of factors, including the difficulty of developing an effective vaccine, the expensive and time-consuming diagnostic process, the necessity of many months of treatment, the increase in HIV-associated tuberculosis, and the emergence of drug-resistant cases in the 1980s.
What country has had the most success reducing the TB mortality rate?
A: China

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Glacial abrasion is commonly characterized by glacial striations. Glaciers produce these when they contain large boulders that carve long scratches in the bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks, lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock.
What helps scientists determine the speed of a glacier?
A: unanswerable

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The final has been played at the rebuilt Wembley Stadium since it opened, in 2007. The rebuilding process meant that between 2001 and 2006 they were hosted at the Millennium Stadium in Cardiff in Wales. Prior to rebuilding, the final was hosted by the original Wembley Stadium since it opened in 1923 (being originally named the Empire Stadium). One exception to this 78 year series of Empire Stadium finals (including five replays) was the 1970 replay between Leeds and Chelsea, held at Old Trafford in Manchester.
When did this stadium open?
A:
it opened, in 2007.