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Complete the sentences with the correct prepositions of time. America's space shuttle program operated ____ 30 years, ____ 1981 ____ 2011. The shuttles flew into space and back. They carried astronauts and equipment. The first space shuttle, Columbia , went into space ____ April 12, 1981. It completed 28 trips. It was in space ____ a total of 300 days. The last shuttle, Atlantis , completed its last flight ____ July 8, 2011. Some of the "retired" shuttles are going to be in museums. For example, Atlantis will be at the Kennedy Space Center in Florida. The exhibit will open to the public ____ July 2013. The shuttle Endeavor flew 25 missions ____ 1981 ____ 2011. Now visitors can see it at the California Science Center in Los Angeles. The exhibit opened ____ Tuesday, October 30, 2012.