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

[EX Q]: Sentence: 'a small bird perched on a open window'. Replace the letter 'e' with 'r' in the sentence.
[EX A]: a small bird prrchrd on a oprn window

[EX Q]: Sentence: 'subway train approaching the platform of a subway station'. Replace the letter 'y' with 'c' in the sentence.
[EX A]: subwac train approaching the platform of a subwac station

[EX Q]: Sentence: 'a couple of brown bears walking across a lush green field'. Replace the letter 'w' with 'o' in the sentence.
[EX A]:
a couple of broon bears oalking across a lush green field