Rule 1: 1. Defective verbs in narrative
Remember the three patterns of lesson 144. ā-verbs (مَضَى، يَمْضِي; أَعْطَى، يُعْطِي; أَلْقَى، يُلْقِي; اِشْتَرَى، يَشْتَرِي) write final ى, show ي before consonant endings (أَعْطَيْتُ), and lose it before ـُوا and ـَتْ (أَعْطَوْا, مَضَتْ). ū-verbs (كَسَا، يَكْسُو to clothe; دَعَا، يَدْعُو) write ا and show و before consonant endings (كَسَوْتُ). i-verbs (لَقِيَ، يَلْقَى; بَقِيَ، يَبْقَى) keep ي in the perfect (لَقِيَتْ, لَقِيتُ) except before ـُوا (بَقُوا). The dual keeps the third radical everywhere: رَمَيَا they two threw, أَلْقَيَانَا they two threw us. In the jussive and imperative the long vowel is cut: لَمْ يَمْضِ, أَعْطِنِي, اُدْعُ.
مَضَتْ سَنَةٌ وَلَمْ يَرْجِعْ أَخِي.
maḍat sanatun wa-lam yarjiʿ akhī
A year passed and my brother did not come back.
مَضَى + ـَتْ → مَضَتْ: the ى drops.
كَسَوْتُهُ ثَوْبًا جَدِيدًا.
kasawtuhu thawban jadīdan
I clothed him in a new garment.
ū-verb: و reappears before ـتُ; two objects.
أَعْطَيْتُ كُلًّا مِنْهُمَا أَلْفَ دِينَارٍ.
aʿṭaytu kullan minhumā alfa dīnārin
I gave each of them a thousand dinars.
ā-verb of Form IV: ي before ـتُ.
أَبَيْتُ أَنْ أُسَافِرَ سِتَّ سِنِينَ.
abaytu an usāfira sitta sinīna
I refused to travel for six years.
أَبَى، يَأْبَى: an ā-verb with a in the imperfect.
أَلْقَى الْأَخَوَانِ أَخَاهُمَا فِي الْبَحْرِ.
alqa l-akhawāni akhāhumā fi l-baḥri
The two brothers threw their brother into the sea.
Verb before a dual subject stays singular.