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 baby elephant in the middle of a field'. Reverse all words of length '3' in the given sentence.
Example Output: a baby elephant in eht middle of a field

Example Input: Sentence: 'a river filled with lots of boats and surrounded by buildings'. Reverse all words of length '4' in the given sentence.
Example Output: a river filled htiw stol of boats and surrounded by buildings

Example Input: Sentence: 'a woman wrapped in a blanket sitting on her bed eating a rice cake'. Reverse all words of length '4' in the given sentence.
Example Output:
a woman wrapped in a blanket sitting on her bed eating a ecir ekac