In the first group, replace the final dammah with sukun. Five pronoun slots are included; two share the written form تَفْعَلُ.
هُوَ: يَفْعَلُ ← يَفْعَلْ
هِيَ: تَفْعَلُ ← تَفْعَلْ
أَنْتَ: تَفْعَلُ ← تَفْعَلْ
أَنَا: أَفْعَلُ ← أَفْعَلْ
نَحْنُ: نَفْعَلُ ← نَفْعَلْ
Worked example: هُوَ يَكْتُبُ ← لَمْ يَكْتُبْ. The ending changes from dammah to sukun; the meaning becomes “He did not write.”