Rule 1: 1. The perfect: و or ي between two vowels becomes ā
Rule 1. When the first radical carries a and the second and third radicals both carry vowels, the second radical (و or ي) with its vowel is replaced by a vowelless alif, that is, by ā: قَوَلَ becomes قَالَ, سَيَرَ becomes سَارَ, خَوِفَ becomes خَافَ, نَوِمَ becomes نَامَ, بَيَعَ becomes بَاعَ. The same thing happens in the perfect of Forms VII and VIII, whose first radical also carries a: اِنْقَوَدَ becomes اِنْقَادَ he submitted, اِخْتَيَرَ becomes اِخْتَارَ he chose, اِحْتَوَجَ becomes اِحْتَاجَ he needed; and in their imperfects and participles, يَخْتَارُ، يَحْتَاجُ، مُخْتَارٌ، مُحْتَاجٌ، مُنْقَادٌ.
قَالَ الْمُسَافِرُ: سَارَ الْقِطَارُ فِي الصَّبَاحِ.
qāla l-musāfiru: sāra l-qiṭāru fi ṣ-ṣabāḥi
The traveller said: the train left in the morning.
قَالَ for قَوَلَ, سَارَ for سَيَرَ.
زَارَ عَمِّي مَكَّةَ وَطَافَ حَوْلَ الْكَعْبَةِ.
zāra ʿammī makkata wa-ṭāfa ḥawla l-kaʿbati
My uncle visited Mecca and walked round the Kaʿba.
Both verbs have و as second radical: ز-و-ر، ط-و-ف.
نَامَ الْأَطْفَالُ فِي الطَّائِرَةِ وَخَافَتْ أُخْتِي مِنَ الطَّيَرَانِ.
nāma l-aṭfālu fi ṭ-ṭāʾirati wa-khāfat ukhtī mina ṭ-ṭayarāni
The children slept on the plane and my sister was afraid of flying.
نَامَ and خَافَ are of the pattern فَعِلَ (نَوِمَ، خَوِفَ).
اِخْتَارَ الْحُجَّاجُ فُنْدُقًا قَرِيبًا مِنَ الْحَرَمِ.
ikhtāra l-ḥujjāju funduqan qarīban mina l-ḥarami
The pilgrims chose a hotel near the Sanctuary.
Form VIII of خ-ي-ر: اِخْتَارَ، يَخْتَارُ، اِخْتِيَارٌ.
اِحْتَاجَ السَّائِحُ إِلَى رَجُلٍ يَعْرِفُ الطَّرِيقَ.
iḥtāja s-sāʾiḥu ilā rajulin yaʿrifu ṭ-ṭarīqa
The tourist needed a man who knew the way.
Form VIII of ح-و-ج.
بَاعَ صَاحِبُ الدُّكَّانِ الْحَقَائِبَ كُلَّهَا.
bāʿa ṣāḥibu d-dukkāni l-ḥaqāʾiba kullahā
The shopkeeper sold all the suitcases.
بَاعَ for بَيَعَ: in the perfect, و-verbs and ي-verbs look exactly alike.