Please answer this: Extract the answer to the question from the following context. Question: What stops countries from choosing all their best professional players? Context: There has been a football tournament at every Summer Olympic Games since 1900, except at the 1932 games in Los Angeles. Before the inception of the World Cup, the Olympics (especially during the 1920s) had the same status as the World Cup. Originally, the event was for amateurs only; however, since the 1984 Summer Olympics, professional players have been permitted, albeit with certain restrictions which prevent countries from fielding their strongest sides. The Olympic men's tournament is played at Under-23 level. In the past the Olympics have allowed a restricted number of over-age players per team. A women's tournament was added in 1996; in contrast to the men's event, full international sides without age restrictions play the women's Olympic tournament.
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Answer: certain restrictions

Please answer this: Extract the answer to the question from the following context. Question: What ways do trees utilize luck? Context: It is remarkable that the inner heartwood of old trees remains as sound as it usually does, since in many cases it is hundreds, and in a few instances thousands, of years old. Every broken limb or root, or deep wound from fire, insects, or falling timber, may afford an entrance for decay, which, once started, may penetrate to all parts of the trunk. The larvae of many insects bore into the trees and their tunnels remain indefinitely as sources of weakness. Whatever advantages, however, that sapwood may have in this connection are due solely to its relative age and position.
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Answer: relative age and position

Please answer this: Extract the answer to the question from the following context. Question: What information is simply background/informational? Context: People can be exposed to asphalt in the workplace by breathing in fumes or skin absorption. The National Institute for Occupational Safety and Health (NIOSH) has set a Recommended exposure limit (REL) of 5 mg/m3 over a 15-minute period. Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with asphalt, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that effect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the asphalt emissions. In particular, temperatures greater than 199 C (390 F), were shown to produce a greater exposure risk than when asphalt was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement.
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Answer:
Asphalt is basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials