TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a man who is surfing in a wave in the ocean'. Replace the letter 'a' with 'u' in the sentence.

SOLUTION: u mun who is surfing in u wuve in the oceun

PROBLEM: Sentence: 'a tennis racket is sitting in the middle of a tennis field'. Replace the letter 'i' with 'f' in the sentence.

SOLUTION: a tennfs racket fs sfttfng fn the mfddle of a tennfs ffeld

PROBLEM: Sentence: 'there is a piece of a cake on the plate and a cup of drink'. Replace the letter 'r' with 'u' in the sentence.

SOLUTION:
theue is a piece of a cake on the plate and a cup of duink