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 couple of giraffes standing in front of a metal fence'. Reverse all words of length '8' in the given sentence.
Example Output: a couple of seffarig gnidnats in front of a metal fence

Example Input: Sentence: 'a hand holds a napkin with a doughnut as potatoes sit in the bathroom'. Reverse all words of length '1' in the given sentence.
Example Output: a hand holds a napkin with a doughnut as potatoes sit in the bathroom

Example Input: Sentence: 'a green bus with a red top traveling down a street'. Reverse all words of length '9' in the given sentence.
Example Output:
a green bus with a red top gnilevart down a street