for, since, from , ago and before

1. For, since and from ‘point forwards’ in time
Ago and before ‘point backwards’ in time.

2. We use for to say how long something lasts

for + period of time

  • I once studied the guitar for three years
  • That house has been empty for six weeks
  • We go away for three weeks every summer.
  • My boss will be in Italy for the next ten days.

When we talk about a period of time up to the present, we use for with the present perfect tense (have+ past participle)

  • I’ve known her for a long time (NOT I know her…)

A present progressive with for often refers to the future.

  • How long are you staying for? (=Until when)

We can leave out for with How long….?

  • How long are you staying?
  • How long have you been waiting?

3. From and since give the starting point of an action or state: they say when something begins or began.

from/ since + starting point

  • I’ll be here from three o’clock onwards.
  • I word  from nine to five.
  • From now on. I’m going to go running every day.
  • From his earliest childhood he loved music
  • I’ve been waiting since ten o’clock.
  • I’ve known her since January.

Since gives the starting point of actions and states that continue up to the present; from gives the starting point of other actions and states

4. For and since can both be used with the present perfect (have + past participle). They are not the same

for+ period

  • I’ve known her for three days.
  • I’ve been here for a month.
  • I’ve had my car for ages.

since + starting point

  • I’ve known her since Tuesday.
  • I’ve been here since July.
  • I’ve had my car since 1980