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 large grouo of people riding on a bunch of motorcycles'. Reverse all words of length '5' in the given sentence.
Example Output: a egral ouorg of people riding on a hcnub of motorcycles

Example Input: Sentence: 'a couple of beds pushed together inside of a hospital'. Reverse all words of length '6' in the given sentence.
Example Output: a elpuoc of beds dehsup together edisni of a hospital

Example Input: Sentence: 'a grass area with rocks on it and several zebra grazing in the grass with trees in the background'. Reverse all words of length '4' in the given sentence.
Example Output:
a grass aera htiw rocks on it and several zebra grazing in the grass htiw trees in the background