TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a u.s. military helicopter landing or taking off'. Replace the letter 'i' with 'l' in the sentence.

SOLUTION: a u.s. mllltary hellcopter landlng or taklng off

PROBLEM: Sentence: 'a room with a bed, lamps, tables and pillows'. Replace the letter 's' with 'b' in the sentence.

SOLUTION: a room with a bed, lampb, tableb and pillowb

PROBLEM: Sentence: 'a fire hydrant near a brick wall'. Replace the letter 'd' with 's' in the sentence.

SOLUTION:
a fire hysrant near a brick wall