At least three things were finished

Something is such that (it was finished and at least two things other than it were finished

∃x (Fx ∧ at least two things other than x were finished)

∃x (Fx ∧ (∃y: ¬ y = x) (∃z: ¬ z = x ∧ ¬ z = y) (Fy ∧ Fz))

∃x ∃y ∃z ((¬ y = x ∧ ¬ z = x ∧ ¬ z = y) ∧ (Fx ∧ Fy ∧ Fz))