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

Example Input: Sentence: 'a couple sits on a bench in the countryside'. Replace the letter 'y' with 'k' in the sentence.
Example Output: a couple sits on a bench in the countrkside

Example Input: Sentence: 'two tennis players shaking hands across the net'. Replace the letter 't' with 's' in the sentence.
Example Output: swo sennis players shaking hands across she nes

Example Input: Sentence: 'a woman in a suit and tie touching a glass'. Replace the letter 'h' with 'g' in the sentence.
Example Output:
a woman in a suit and tie toucging a glass