for / since and How long…?

Rules

• Rule 1: for + a period

  for tells us the length of time: how many minutes, days or years.

  Pattern: for + period of time

  Example: I've had my bike for two years.

  Example: We've been here for ten minutes.

• Rule 2: since + a starting point

  since tells us when it started: a day, a date or an event.

  Pattern: since + starting point

  Example: I've known her since 2021.

  Example: He's been happy since he got a puppy.

• Rule 3: How long…?

  To ask about the length of time, use How long + present perfect.

  Pattern: How long have / has + subject + past participle?

  Example: How long have you had that bag?

  Example: How long has she lived here?

Common mistakes

• I live here for five years. → I have lived here for five years.

  Duration up to now → present perfect.

• I've known him since three years. → I've known him for three years.

  A period → for.

• She has been here for Monday. → She has been here since Monday.

  A starting day → since.