Here's why:
* Spelling: The "a" in "stand" is followed by the letter "n." In most cases, when a vowel is followed by a consonant and then a silent "e," it makes a long vowel sound.
* Pronunciation: The "a" in "stand" is pronounced as a long "a" sound, similar to the "a" in "stay" or "face."
Therefore, the vowel sound in "stand" is not short, but long.