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 person in a rowboat under an umbrella'. Reverse all words of length '5' in the given sentence.
a person in a rowboat rednu an umbrella

Sentence: 'a pair of bikers riding past a kite store'. Reverse all words of length '6' in the given sentence.
a pair of srekib gnidir past a kite store

Sentence: 'a giraffe is in a small steel cage'. Reverse all words of length '7' in the given sentence.

a effarig is in a small steel cage