is not sufficiently; is not ... enough
La estructura no es lo suficientemente fuerte como para soportar tanto peso.
The structure isn’t strong enough to support that much weight.
María dice siempre que Tom no es lo suficientemente romántico.
María always says that Tom isn't romantic enough.
Tal vez, todavía no es lo suficientemente fuerte.
Maybe, he's not strong enough yet.
Quizá sea porque la luna no es lo suficientemente brillante.
Maybe it’s because the moon isn’t bright enough.
Tom no es lo suficientemente estricto con sus alumnos.
Tom isn't strict enough with his students.
Ella no es lo suficientemente buena para él.
She isn’t good enough for him.
Un plátano verde no es lo suficientemente maduro para comer.
A green banana isn't ripe enough to eat.
No es lo suficientemente disciplinado.
He isn't disciplined enough.