TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a herd of cattle standing on a lush green field'. Replace the letter 'g' with 'f' in the sentence.

SOLUTION: a herd of cattle standinf on a lush freen field

PROBLEM: Sentence: 'two men running for a soccer ball on a field'. Replace the letter 'd' with 'a' in the sentence.

SOLUTION: two men running for a soccer ball on a fiela

PROBLEM: Sentence: 'a motorcycle sitting on the tar, with other bikes behind it'. Replace the letter 'o' with 'c' in the sentence.

SOLUTION:
a mctcrcycle sitting cn the tar, with cther bikes behind it