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

Sentence: 'a close up of a train on train tracks at night'. Replace the letter 'n' with 'm' in the sentence.
a close up of a traim om traim tracks at might

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 downhill skier on skis in a crouched position'. Replace the letter 'n' with 'x' in the sentence.

a dowxhill skier ox skis ix a crouched positiox