1. I haven't seen my friend since ...

Ответ (EN)

• I haven't seen my friend since last year.

Обоснование: 'Since' usually refers to a point in time or a period that started in the past and continues to the present. 'Last year' is a common time reference used with 'since'.

Перевод (RU)

• Я не видела моего друга с прошлого года.