The prefix ي appears in exactly 4 forms:
• the 3 masculine Ghaa'ib forms
• the plural feminine Ghaa'ib form
ExamplePosition
يَفْعُلُmasculine Ghaa'ib — singular
يَفْعُلَانِmasculine Ghaa'ib — dual
يَفْعُلُونَmasculine Ghaa'ib — plural
يَفْعُلْنَfeminine Ghaa'ib — plural