ils tremblaient

were trembling, used to tremble

→ trembler
trembl to tremble, to shake + aient they were ...ing (imperfect past)
verb · third plural · imperfect indicative Rare #40,554
were trembling, used to tremble Imperfect tense (3rd person plural): ongoing or habitual action in the past.
FR: Ils tremblaient de froid.
EN: They were trembling with cold.
Conjugation of trembler
Indicative imperfect
SingularPlural
First tremblais
Second tremblais
Third tremblait tremblaient

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.

Mes jambes tremblaient.

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.