Выберите правильную глагольную форму: a. have studied; b. had studied; c. am studying; d. study; e. have been studying; f. had been studying; was studying

11. I ……………every day.
12. I ……………right now. Chapter Two.
13. I ……………for two hours.
14. I ……………Chapter One.
15. I ………Chapter One before I began to study
16. I ………last night, when mother came.
17. I……….for 4 hours, when mother came.