Unit 12. When…? and How long…? For and since
(сравнение Past Simple и Present Perfect)
…? (+ Past Simple
) and How long
…? (+ Present Perfect
|A: When did it start raining?
B: It started raining an hour ago / at 1 o'clock.
A: How long has it been raining?
B: It's been raining for an hour / since 1 o'clock.
|A: When did Joe and Carol first meet?
B: They first met a long time ago / when they were at school.
A: How long have Joe and Carol known each other?
|B: They've known each other
||for a lone time.
since they were at school.
We use both for
to say how long something has been happening.
|We use for when we say a period of time (two hours, six weeks etc.):
- I've been waiting for two hours.
- Sally's been working here for six months. (not since six months)
- I haven't seen Tom for three days. (not since three days)
|We use since when we say the start of a period (8 o'clock, Monday, 1985 etc.):
- I've been waiting since 8 o'clock.
they were at school
- Sally's been working here since April. ( = from April until now)
- I haven't seen Tom since Monday. ( = from Monday until now)
It is possible to leave out for
(but not usually in negative sentences):
- They've been married (for) ten years. (with or without for)
- They haven't had a holiday for ten years. (you must use for)
We do not
use for + all … (all day / all my life
- I've lived here all my life. (not for all my life)
We say "It's
(a long time / two years etc.) since
- It's two years since I last saw Joe. ( = I haven't seen Joe for two years / the last time I saw Joe was two years ago)
- It's ages since we went to the cinema. ( = We haven't been to the cinema for ages)
The question is How long is it since …
- How long is it since you last saw Joe? ( = When did you last see Joe?)
- How long is it since Mrs ill died? ( = When did Mrs Hill die?)
See Unit 11. How long have you (been)…?
(настоящее совершенное время).