12. My sister (not to play) the piano at four o'clock yesterday. She (to play) the piano the whole evening.

12. My sister (not to play) the piano at four o'clock yesterday. She (to play) the piano the whole evening.

В первом предложении нужно использовать Past Continuous в отрицательной форме: My sister was not playing the piano at four o'clock yesterday. Во втором предложении нужно использовать Past Continuous в утвердительной форме: She was playing the piano the whole evening.

Перевод: Моя сестра не играла на пианино в четыре часа вчера. Она играла на пианино весь вечер.

Ответ: My sister was not playing the piano at four o'clock yesterday. She was playing the piano the whole evening.