In this task, you need to reverse all words of a given length in the sentence. The number of letters in a word determine its length. For example, the length of the word "apple" is 5.
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Question: Sentence: 'a man assisting a person on a horse on a race track'. Reverse all words of length '3' in the given sentence.

Answer: a nam assisting a person on a horse on a race track


Question: Sentence: 'an elderly man in a jacket is walking outside of a window'. Reverse all words of length '3' in the given sentence.

Answer: an elderly nam in a jacket is walking outside of a window


Question: Sentence: 'everyone is waiting in line to purchase tickets'. Reverse all words of length '8' in the given sentence.

Answer:
enoyreve is waiting in line to esahcrup tickets