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.

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

Sentence: 'a couple of women sitting on a bench with a dog'. Reverse all words of length '4' in the given sentence.
a couple of women sitting on a bench htiw a dog

Sentence: 'a herd of elephants walking along a river'. Reverse all words of length '5' in the given sentence.

a herd of elephants walking gnola a revir

