7. You ......... respect your teachers and your classmates. You ......... talk or eat in class. She ......... have watered the garden as I had already done it. Ian ......... have finished his homework already, it's impossible.

Решение:

• 1. You must respect your teachers and your classmates. (Выражает обязательство).
• 2. You mustn't talk or eat in class. (Выражает запрет).
• 3. She should have watered the garden as I had already done it. (Выражает сожаление о несделанном действии, которое было бы уместным).
• 4. Ian can't have finished his homework already, it's impossible. (Выражает невозможность или сильное сомнение).

Ответ: must, mustn't, should, can't.