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

Sentence: 'three colorful knit bear toys with button eyes'. Replace the letter 'r' with 'z' in the sentence.
thzee colozful knit beaz toys with button eyes

Sentence: 'a building has a clock on the top of it'. Replace the letter 'l' with 'x' in the sentence.
a buixding has a cxock on the top of it

Sentence: 'a mixed bouquet of flowers in a glass vase set before a window'. Replace the letter 's' with 'r' in the sentence.

a mixed bouquet of flowerr in a glarr vare ret before a window