In this task, you need to replace a letter in the sentence with another given letter.
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Question: Sentence: 'a man is standing on a snowboard, atop a mountain'. Replace the letter 'd' with 'u' in the sentence.

Answer: a man is stanuing on a snowboaru, atop a mountain

Question: Sentence: 'a long green grain traveling past a white building'. Replace the letter 'w' with 'o' in the sentence.

Answer: a long green grain traveling past a ohite building

Question: Sentence: 'a machine is digging as a group of people look on'. Replace the letter 'i' with 'z' in the sentence.

Answer:
a machzne zs dzggzng as a group of people look on