Может вопросы? У меня в учебнике написано про ответы. Ты перепутал задания :).
Вот первый ответ (ОБЩИЙ) : Did Alex clean his room yersterday?
Вот несколько других:
What did Alex clean yersterday?
When did Alex clean his room?
Whose room did Alex clean yersterday?
What did Alex do yersterday?
Who cleaned his room yersterday?
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Удачи! И не путай задания!