3. While my brother was learning the poem, I...

Необходимо вставить подходящее по смыслу продолжение предложения.

Смысл: в то время, как брат учил стихотворение, я играл на гитаре.

While my brother was learning the poem, I - the guitar at 9 o'clock yesterday.

Ответ: the guitar at 9 o'clock yesterday