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: 'pretty young dark haired girl sitting in an amusement ride holding her teddy'. Reverse all words of length '7' in the given sentence.

pretty young dark haired girl gnittis in an amusement ride gnidloh her teddy