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

Sentence: 'a family opens gifts in a room with their dog, while sitting on couches'. Replace the letter 's' with 'l' in the sentence.
a family openl giftl in a room with their dog, while litting on couchel

Sentence: 'a group of three giraffes standing around a fence'. Replace the letter 't' with 'a' in the sentence.
a group of ahree giraffes saanding around a fence

Sentence: 'group with papers and table with computer and board'. Replace the letter 'c' with 'x' in the sentence.
group with papers and table with xomputer and board