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.

Sentence: 'a blue sign sitting on the side of a road next to a tree'. Reverse all words of length '1' in the given sentence.
a blue sign sitting on the side of a road next to a tree

Sentence: 'a group of zebras gather at a watering hole'. Reverse all words of length '1' in the given sentence.
a group of zebras gather at a watering hole

Sentence: 'a baseball field with a lot of people on it'. Reverse all words of length '3' in the given sentence.

a baseball field with a tol of people on it