It is often difficult for learners of English to know when to use ‘for’, ‘since’ and ‘ago’.
Here is a short explanation with examples.

  • For is used to indicate a period of time.
    • How long are you staying in London? I’m staying for a week.
  • For is often used with the Present Perfect.
    • I have been waiting at the bus stop for 10 minutes.
    • I have lived in this country for 5 years.
  • For can be used with other verb tenses :
    • Present : I go on holidays for two weeks every summer.
    • Past : When I was sixteen, I stayed in London for two months.
    • Future :While I am in the USA , I will be in New York for two days.
  • Since is used to refer to the starting point of actions or situations.
    It is generally used with the Present Perfect.
    • I have been waiting for the bus since 8 o’clock.
    • I live in Tokyo. I have lived in Tokyo since January 2010.
    • I have been learning English since the beginning of the year.
  • Ago is used to say when past events happened, going back from today towards the past. The verb is in the Past Tense.
    • I came to Tokyo two years ago.
    • I arrived at the bus stop 10 minutes ago.
    • The company was founded 30 yearsago.