Here's why:
* Long vowels are typically represented by a single vowel letter followed by a silent "e" at the end of a word (like "cake", "hope", "bike").
* R-controlled vowels have a different sound quality because the "r" influences the vowel sound. The vowel sound is shortened and often has a different quality altogether.
Examples:
* "car" - The vowel sound is not a long "a" sound, but rather a short, slightly "r"-colored sound.
* "bird" - The vowel sound is not a long "i" sound, but a short, "r"-colored sound.
* "fur" - The vowel sound is not a long "u" sound, but a short, "r"-colored sound.
In summary: R-controlled vowels create unique sounds, different from both long and short vowel sounds.