Here's why:
* The vowel "a" in "card" is followed by a consonant ("rd"). This is a key indicator of a short vowel sound.
* The "a" in "card" does not have the long "a" sound like in words like "cake" or "rain."
Therefore, the "a" in "card" makes a short "a" sound, like the "a" in "cat" or "hat."