Final answer:
To describe events that happened in the past in relation to other past events, we use the past perfect tense. In this case, we would use the past perfect tense 'had woken up' for the first verb, and the simple past tense 'prepared' for the second verb.
Step-by-step explanation:
To describe events that happened in the past in relation to other past events, we use the past perfect tense. In this case, we would use the past perfect tense 'had woken up' for the first verb, and the simple past tense 'prepared' for the second verb. So the sentence would be: 'When he had woken up, his mother had already prepared breakfast.'
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