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 group of sheep graze in a grassy field'. Reverse all words of length '2' in the given sentence.
a group fo sheep graze ni a grassy field

Sentence: 'many vegetables are on the green kitchen counter'. Reverse all words of length '7' in the given sentence.
many vegetables are on the green nehctik retnuoc

Sentence: 'the elephant in the grass is heading for the water source'. Reverse all words of length '5' in the given sentence.

the elephant in the ssarg is heading for the retaw source