Use these clues as a reading aid, not as isolated memorization:
● ـَا often marks masculine dual third person: كَتَبَا.
● ـُوا marks masculine plural third person: كَتَبُوا.
● ـَتْ marks feminine singular third person: كَتَبَتْ.
● ـْنَ marks feminine plural third person: كَتَبْنَ.
● Endings beginning with ت commonly mark addressed forms or ـْتُ for “I.”
● ـْنَا marks “we”: كَتَبْنَا.