I was too astonished to speak.
- Je suis resté sans voix tellement j'étais étonné.
I was astonished by his ignorance.
- J'étais étonné de son ignorance.
I am amazed at your audacity.
- Je suis étonné par ton audace.
Tom was amazed at the huge amount of his personal information which had been gleaned by Google based on his internet usage.
- Tom fut étonné de l'énorme quantité de renseignements personnels qui avaient été recueillies par Google basé sur son utilisation d'Internet.