Here's why:
* Spelling: The word "bee" has a single vowel letter "e" at the end of the word. This is a common indicator of a long vowel sound.
* Pronunciation: The "ee" sound in "bee" is a long, drawn-out sound, similar to the sound of "see" or "tree".
* Contrast: Compare it to words like "bet" or "bed", where the vowel sound is short and clipped.
So, the "ee" in "bee" is a long vowel sound.