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

Sentence: 'a wooden bench sits on top of a grass hill'. Reverse all words of length '2' in the given sentence.
a wooden bench sits no top fo a grass hill

Sentence: 'a male and female skier posing at the top of a hill in front of snowy mountains'. Reverse all words of length '4' in the given sentence.

a elam and female skier posing at the top of a llih in front of snowy mountains