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

Sentence: 'a crowd stands under a set of lights in the ceiling and one person holds up a cell phone'. Replace the letter 'r' with 'f' in the sentence.
a cfowd stands undef a set of lights in the ceiling and one pefson holds up a cell phone

Sentence: 'a fancy clock is lit up on the street'. Replace the letter 'o' with 'f' in the sentence.
a fancy clfck is lit up fn the street

Sentence: 'a closed umbrella sitting on a balcony ledge above traffic'. Replace the letter 'o' with 'i' in the sentence.

a clised umbrella sitting in a balciny ledge abive traffic