Here's why:
* The vowel sound in "gave" is a short "a" sound. It sounds like the "a" in "cat" or "hat".
* Long vowel sounds are typically associated with a vowel followed by a silent "e" at the end of the word (like "bake", "hope", "time").
So, while "gave" has a "a" in it, it's not a long vowel sound.