was shaking, was trembling
Temblaba cada vez que ella hablaba.
He trembled every time she spoke.
— El cartero (y Pablo Neruda) (1994)
El muchacho estaba muy pálido, y todo su cuerpo temblaba de frío.
The boy was very pale, and his whole body was trembling with cold.
Su mano temblaba cuando tomó el bolígrafo para firmar.
His hand was trembling when he picked up the pen to sign.