In the 1870's when Marx was already in his fifties, he found it important to study the situation in Russia, so he began to learn Russian.

在十九百年七十年代当马克思已经半百多岁时，他发现研究俄国的形势很重要，便开始学习俄语。

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By the middle nineteen fifties, Doctor Seuss had become one of the best-loved and most successful children's book writers in the world.

VOA: special.2010.05.02

J.Robert Oppenheimer's life and work were affected deeply by Americans intense fear of Communism in the nineteen fifties.

VOA: special.2009.06.14

Kahn's first important project was the Yale Art Gallery in New Haven,Connecticut in the early nineteen fifties.

VOA: special.2009.12.13

Brown also appears on one of the most significant occasions in Blue Note's fifties catalogue: the live recording of the Art Blakey Quintet, from Birdland, one of the leading clubs in New York.

NPR: 'Blue Note Records, The Biography'

When U.S. obscenity laws were first relaxed, in the fifties, no special stipulations were made for photographs of minors.

NEWYORKER: The Science of Sex Abuse

Describes Emil Freireich's research into drugs to treat acute lymphoblastic leukemia (ALL) in the nineteen-fifties and sixties.

NEWYORKER: The Treatment