3. For and Since
- We use for and since with the past perfect to indicate the duration of a past state or a past action.

- We use for to refer to the period of time a state or an action has lasted, without referring to the exact moment when it began.

Ex: Liz Potts has worked as a cool hunter for several years.

- We use since to refer to the specific moment when a state or an action began.
Ex: How many pairs of sneakers have you bought since last year?
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1 - I haven’t spoken to my friend for three days.
2 – I’ve had these shoes since last month.
3 – I’ve been awake since the 10 p.m.
4 – I’ve been interested in music for five years.
5 – I haven’t been to the beach for two months.
6 – I‘ve known my classmates for four years.
7 – I’ve spoken Spanish since 2001.
8 – I haven’t seen a film at the cinema since last month.