Here's why:
* Modern Greek uses the Modern Greek alphabet, a modified version of the ancient Greek alphabet. This alphabet has 24 letters.
* Ancient Greek was written in the Ancient Greek alphabet, which had 24 letters but differed in some of its characters.
So, while the same language (Greek) uses different alphabets, it's not technically using multiple alphabets at the same time.
Other languages that have used multiple alphabets over time include:
* Russian: While modern Russian uses the Cyrillic alphabet, it historically used the Glagolitic and Cyrillic alphabets.
* Serbian: Serbian uses both the Cyrillic and Latin alphabets, with both being considered official.
It's important to note that these are just a few examples, and there are likely other languages with similar situations.