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Twenty is a score so twenty years is a score of years.
This year or from previous years?
Twenty Years After was created in 1845.
The annual snowfall in Edgewood, New Mexico averages around 23 inches. Snowfall can vary from year to year, with some years receiving more or less snowfall than the average.
Joseph was either in prison for twenty years or in Egypt for twenty years. But I think it was Joseph in Egypt for twenty years.
Twenty Years of Dirt was created in 1986.
Twenty One Years was created in 2006.
Twenty Good Years was created in 2006.
The Twenty Years' Crisis was created in 1939.
Musketeers Twenty Years After was created in 1992.
That is the correct spelling of the period of "twenty-seven years" (27 years).
Twenty years old is はたち