Original Question:
By the end of the Apollo program , twelve Americans have walked on the moon.
Correct Question:
By the end of the Apollo program , twelve Americans had walked on the moon.
Doubt:Why we could not have used just the Past Tense walked . Above the time reference is very clear (by the end of the Apollo program).
By the end of the Apollo program , twelve Americans have walked on the moon.
Correct Question:
By the end of the Apollo program , twelve Americans had walked on the moon.
Doubt:Why we could not have used just the Past Tense walked . Above the time reference is very clear (by the end of the Apollo program).
















