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: 'an orange and white bus driving down a city street'. Reverse all words of length '1' in the given sentence.
an orange and white bus driving down a city street

Sentence: 'a man walking a brown horse down a race track'. Reverse all words of length '4' in the given sentence.
a man walking a brown horse nwod a ecar track

Sentence: 'a long line of people standing in the rain beneath umbrellas'. Reverse all words of length '9' in the given sentence.

a long line of people standing in the rain beneath sallerbmu