10. What...... you doing when your father came? A. was B. were C. are

Решение:

Вопрос задан во времени Past Continuous. Используется вспомогательный глагол 'was' или 'were' в зависимости от подлежащего. Подлежащее 'you' требует формы 'were'.

Ответ: B. were