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 bird sitting in a tree next to a citrus fruit'. Reverse all words of length '6' in the given sentence.
Example Output: a bird sitting in a tree next to a surtic fruit

Example Input: Sentence: 'a guy on  a surf board by a very big wave'. Reverse all words of length '3' in the given sentence.
Example Output: a yug on a surf board by a very gib wave

Example Input: Sentence: 'a fed ex plan is getting ready to take off and deliver packages'. Reverse all words of length '8' in the given sentence.
Example Output:
a fed ex plan is getting ready to take off and deliver segakcap