Rule 1: 1. The vocative أَيُّهَا
To address a person or a group by a common noun, Arabic uses أَيُّهَا (feminine أَيَّتُهَا) followed by the noun with the article and in the nominative: أَيُّهَا الْمَلِكُ O king, أَيَّتُهَا الْبِنْتُ O girl. In the Quran and in formal speech يَا is often placed in front as well: يَا أَيُّهَا النَّاسُ. Compare يَا with a name, where the noun has no article and no tanwīn: يَا سَلْمَى, يَا وَلَدُ.
أَيُّهَا الشَّيْخُ، لِمَاذَا تَزْرَعُ الْيَوْمَ؟
ayyuha-sh-shaykhu, li-mādhā tazraʿu-l-yawma?
O sheikh, why are you sowing today?
أَيُّهَا الْمَلِكُ، اَلْمَطَرُ مِنْ عِنْدِ اللّٰهِ.
ayyuha-l-maliku, al-maṭaru min ʿindi-llāhi
O king, the rain is from God.
أَيُّهَا التَّلَامِيذُ، اِفْتَحُوا كُتُبَكُمْ.
ayyuha-t-talāmīdhu, iftaḥū kutubakum
Pupils, open your books.
أَيَّتُهَا الْأُمُّ، اِبْنُكِ فِي الْحَقْلِ.
ayyatuha-l-ummu, ibnuki fi-l-ḥaqli
O mother, your son is in the field.
Feminine أَيَّتُهَا.
يَا سَلْمَى، أَيْنَ أَبُوكِ؟
yā salmā, ayna abūki?
Salma, where is your father?
A name takes يَا alone.