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 green apple and knife on dark wooden stairs'. Reverse all words of length '3' in the given sentence.
a green apple dna knife on dark wooden stairs

Sentence: 'pair of dogs watching television in living area of home'. Reverse all words of length '8' in the given sentence.
pair of dogs gnihctaw television in living area of home

Sentence: 'a very happy man and lady laying in a bed'. Reverse all words of length '6' in the given sentence.

a very happy man and lady gniyal in a bed