Réponse:

Salut,

A. She must have seen me.

B. It must have been very expensive.

C. They must have gone away.

D. I must have leaved it in the restaurant last night.

E. The exam mustn't have been very difficult.

F. She must have listened to our conversation.

G. She mustn't has understood what I said.

H. I must have forgotten to turn it off.

I. The driver mustn't has seen the red light.

J. The neighbors must have had a party.