Premise: Alan Shepard . He was Chief of the Astronaut Office from November 1963 to July 1969 ( the approximate period of his grounding ) , and from June 1971 until his retirement from the United States Navy and NASA on August 1 , 1974 .
Hypothesis: Alan Shepard was Chief of the Astronaut Office from November 1963 to July 1969.
Label: ENTAILMENT