Definition: 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.
Input: Sentence: 'person in a khaki shirt with a white frisbee on their face in a park'. Reverse all words of length '7' in the given sentence.

person in a khaki shirt with a white eebsirf on their face in a park