Quidquid id est, timeō Danaōs et dōna ferentēs.”    Sīc fātu…

Quidquid id est, timeō Danaōs et dōna ferentēs.”    Sīc fātus validīs ingentem vīribus hastam     in latus inque ferī curvam compāgibus alvum    contorsit. Stetit illa tremēns, uterōque recussō    īnsonuēre cavae gemitumque dedēre cavernae.    Et, sī fāta deum, sī mēns nōn laeva fuisset,    impulerat ferrō Argolicās foedāre latebrās,    Troiaque nunc stāret, Priamīque arx alta manērēs.   The verb ‘insonuere’ in line 5 is shortened or syncopated. What is the unsyncopated form of this verb?

Quidquid id est, timeō Danaōs et dōna ferentēs.”    Sīc fātu…

Quidquid id est, timeō Danaōs et dōna ferentēs.”    Sīc fātus validīs ingentem vīribus hastam     in latus inque ferī curvam compāgibus alvum    contorsit. Stetit illa tremēns, uterōque recussō    īnsonuēre cavae gemitumque dedēre cavernae.    Et, sī fāta deum, sī mēns nōn laeva fuisset,    impulerat ferrō Argolicās foedāre latebrās,    Troiaque nunc stāret, Priamīque arx alta manērēs.   What does ‘illa’ refer to in line 4?