instruction:
In this task, you need to replace a letter in the sentence with another given letter.
question:
Sentence: 'a train traveling through a dark tunnel next to green brush.'. Replace the letter 'r' with 'e' in the sentence.
answer:
a teain teaveling theough a daek tunnel next to geeen beush.


question:
Sentence: 'a skier with his legs covered in snow lifts one of his feet to stamp it'. Replace the letter 's' with 'y' in the sentence.
answer:
a ykier with hiy legy covered in ynow lifty one of hiy feet to ytamp it


question:
Sentence: 'a young boy holding a skateboard in front of him'. Replace the letter 'n' with 'g' in the sentence.
answer:

a yougg boy holdigg a skateboard ig frogt of him