 This system also produces separate "strong" and "weak" forms of the verb — the strong "guṇa" form is used with the singular active, and the weak zero-grade form with the rest.In some verbs, the 3rd and optionally 1st person are further strengthened until the root syllable becomes heavy.Most verbs ending in consonants behave as "seṭ" in the perfect tense in front of consonant endings.