Реши задание на изображении

Ответ: had closed

Полное предложение:
If you had closed the book on time, the teacher would not have noticed your cheating.

Это условное предложение третьего типа: речь идёт о нереальном условии в прошлом.

• if + Past Perfect: had closed;
• результат: would have + V³: would not have noticed.

Проверка: close — closed — closed, поэтому форма had closed верна.