were trembling, used to tremble
J'ai remarqué que ses mains tremblaient.
I noticed that his hands were trembling.
Ses mains tremblaient lorsqu'il a commencé à parler.
His hands were trembling when he began to speak.
My legs were shaking.
Je gardais les mains dans mes poches parce qu'elles tremblaient trop.
I kept my hands in my pockets because they were shaking too much.
— Assurance sur la mort (1944)
Tom avait les mains qui tremblaient.
Tom’s hands were shaking.