Here's why:
* The vowel "oo" in "stood" is pronounced as a short "u" sound. This is a common pronunciation for "oo" when it follows a consonant.
* Long vowel sounds are typically represented by a double vowel or a vowel followed by a silent "e". For example, "see", "tree", "boat", "moon", etc.
Therefore, "stood" does not have a long vowel sound.