(1) It is twenty years since I have seen her – Is this grammatically accurate? What does it mean?
I don’t think that it is grammatically accurate. For academic writing and in testing, you should consider the above sentence grammatically incorrect. However, Cambrige online dictionary states that we can use the past simple, present perfect or past perfect after since with the expression it + be + time + since:
I still have doubt about it after reading what's written on the website. Just to confirm, I asked some of my colleagues and friends who were English majors and they all shared the same viewpoints as mine.
To err on the safe side, if you want to say “我已經20年沒見她了”, I would say “It has been twenty years since I last saw her.”
It has been twenty years since I last saw her = 我已經20年沒見她了
=> The period of time between the last time that I saw her and today is twenty years. Twenty years have passed, counting from the time I saw her previously to today.
=> I have not seen her for twenty years.
=> It indicates that the last time I saw her was twenty years ago.
If you want to say “這20年來我都有去探望她”, I would say “I have been visiting her for the past twenty years.” (I will continue to visit her)
If you want to say “這20年來我都有與她約會交往”, I would say “I have been seeing her for the past twenty years.” (I will continue to date her)
(2) How about “It is twenty years since I saw her”?
The meaning of “It is twenty years since I last saw her” is the same as that of “It has been twenty years since I last saw her”.
For tense simplification, sometimes, we use present tense to replace present perfect tense.
Written by Elisa English
On October 18th, 2012