Временная форма:
Отрицательная форма:
Общий вопрос:
Специальный вопрос:

Внизу ответ

Объяснение:

My mother played the piano at 3 o'clock

My mother wasn't playing the piano at 3 o'clock

Was my mother playing the piano at 3 o'clock

Did my mother play the piano at 3 o'clock

My mother was playing the piano at 3 o′clock yesterday.

Временная форма: Past Continous

Отрицательная форма: My mother was not playing the piano at 3 o′clock yesterday.

Общий вопрос: Was my mother playing the piano at 3 o′clock yesterday?

Специальный вопрос: When was my mother was playing the piano?