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.

Example Input: Sentence: 'a man walking a brown horse down a race track'. Reverse all words of length '4' in the given sentence.
Example Output: a man walking a brown horse nwod a ecar track

Example Input: Sentence: 'a bird sits atop a post near a boat dock with large boats in the background'. Reverse all words of length '1' in the given sentence.
Example Output: a bird sits atop a post near a boat dock with large boats in the background

Example Input: Sentence: 'a skier skiing downhill at an olympic event'. Reverse all words of length '5' in the given sentence.
Example Output:
a reiks skiing downhill at an olympic tneve