The celebration of Labour Day, in honour of the working class, was______ in the United States in 1882.
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The invention of the printing press set _________ a social revolution that is still in progress.
The tour descriptions are quite detailed and include comprehensive day-by day _________.
Many old statues in that temple that have long been _______ have lost their paint and grown dark with age.
The Appolo Program involved many smaller programs, which engineers used to develop the techniques needed for the _______ trip to the moon.