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: 'an airplane is hooked up to the passenger walkways at an airport'. Reverse all words of length '9' in the given sentence.

an airplane is hooked up to the regnessap walkways at an airport