4. At 12 o'clock I (do) my homework. Mum (cook) lunch.

<p>Here's the solution:</p> <ol> <li>At 12 o'clock I <strong>was doing</strong> my homework. Mum <strong>was cooking</strong> lunch.</li> </ol><p><strong>Ответ:</strong> At 12 o'clock I <strong>was doing</strong> my homework. Mum <strong>was cooking</strong> lunch.</p>