In this task, you need to replace a letter in the sentence with another given letter.

[EX Q]: Sentence: 'a train traveling through a dark tunnel next to green brush.'. Replace the letter 'r' with 'e' in the sentence.
[EX A]: a teain teaveling theough a daek tunnel next to geeen beush.

[EX Q]: Sentence: 'a row of lawn chairs with umbrellas over them'. Replace the letter 'e' with 'x' in the sentence.
[EX A]: a row of lawn chairs with umbrxllas ovxr thxm

[EX Q]: Sentence: 'there are a lot of sheeps walking together in the grass'. Replace the letter 't' with 'l' in the sentence.
[EX A]:
lhere are a lol of sheeps walking logelher in lhe grass