Final answer:
The correct past participle for the sentence is 'inondé', which means 'flooded' in English.
Step-by-step explanation:
The correct past participle for the sentence 'Un terrible tsunami a inondé les côtes de l'Indonésie ce week-end.' is 'inondé'.
'Inondé' is the conjugation of the verb 'inonder' in the past participle form, which means 'flooded' in English. It accurately describes the action of a terrible tsunami flooding the coasts of Indonesia.
For example, we could say 'Les maisons ont été inondées par le tsunam' to mean 'The houses were flooded by the tsunami'.
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