The 20th century
In the late 19th and early 20th century oil was distilled to produce kerosene for lanterns and the byproducts was gasoline
20th
When the 19th century finished. In 1901.
1999 is in the 20th Century. The first year of the 21st century is 2001.
It first appeared in the 20th century
al khwarizmi in the 20th century
20th century.......a bit obvious
20th century in America
20th century
Since the moon walk of Apollo 11 took place in 1969, and that was part of the 20th century, it is *not* an event that did *not* take place in the 20th century.
The first president to be elected in the 20th century was assassinated in 1901, so it is not possible for him to have been president in 1968.