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.
Q: Sentence: 'a very long sub sitting on a table that is too small for it'. Reverse all words of length '3' in the given sentence.
A: 
a very long bus sitting on a table that is oot small rof it