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: 'the plane is ready to take off as the people are watching'. Reverse all words of length '5' in the given sentence.

the enalp is ydaer to take off as the people are watching