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Every winter in Alaska a race is held. But this is no ordinary race. Teams of dogs pull sleds（雪橇）along the snow and ice, (carry) up to 500 kg of supplies. A single driver is in charge of each team, and stands on the sled. This race (know) as Iditarod runs from the town of Anchorage to the village of Nome, a journey of more than l,800 kilometers. It usually takes the teams about ten days to complete the course.
The Iditarod is usually run in(extreme) difficult weather conditions.Daytime (temperature) range from zero to minus 40 degrees. Visibility（能见度）is often very poor, so drivers never allow (them) to become separated from their team of dogs., the drivers depend almost entirely on the dogs for their survival.
The origin of the race(go) back many years to a timesome medicine needed to be taken from Anchorage to Nome, a very remote village. Because of severe weather, the only way to send the medicine(be) to use dogs. Happily, the medicine was delivered justtime to save lives. To celebrate the heroic journey, Alaskans developed the Iditarod.