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 people wearing skis and standing at the top of a ski slope'. Reverse all words of length '7' in the given sentence.
a group of people gniraew skis and standing at the top of a ski slope

Sentence: 'there is a sign stating that there is a scenic drive'. Reverse all words of length '4' in the given sentence.
there is a ngis stating taht there is a scenic drive

Sentence: 'a person riding a black horse on a path beside snow covered trees'. Reverse all words of length '4' in the given sentence.

a person riding a black horse on a htap beside wons covered trees