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 green apple and knife on dark wooden stairs'. Reverse all words of length '3' in the given sentence.
Example Output: a green apple dna knife on dark wooden stairs

Example Input: Sentence: 'a man riding skis down a snow covered slope'. Reverse all words of length '5' in the given sentence.
Example Output: a man riding skis down a snow covered epols

Example Input: Sentence: 'a couple of elephants are standing in the distance'. Reverse all words of length '9' in the given sentence.
Example Output:
a couple of stnahpele are standing in the distance