AGO, BEFORE, FOR, SINCE
You use ago to connect a time in the past with the moment of speaking. If you are speaking on Friday and you say that something happened two days ago, you mean that it happened on Wednesday.
1. The land was acquired by the University two years ago.
2. I discovered a few days ago that Weiss was Houdini’s real name.
You use before to connect a time in the past with a more recent time in the past. If you are talking about what you did last Wednesday and you say that you met someone two days before, you mean that you met them last Monday.
3. She said that, about six months before, she had gone to see an aunt who lived in Stoneyvale.
4. …a woman he had first met twenty minutes before.
You use for to say how long a period lasts in the past, present, or future. If you say that you have been doing something for two days, you mean that you have spent the last two days doing it all the time or part of the time.
5. She sat down and remained absolutely still for nearly half an hour.
6. He had disappeared for three weeks after that.
7. It will ruin us for several years.
You also use for to say how much time passes without something happening. If you are speaking on Friday and you say that you have not done something for two days, you mean that the last time you did it was on Wednesday.
8. I hadn’t seen him for four years.
9. He couldn’t bring himself to eat their food, and he hadn’t eaten for days.
You use since to say when a period started. If you are speaking on Friday and you say that you have been doing something since Wednesday, you mean that you have spent the last two days doing it.
10. She had been a manager of Fairacre School since the reign of King Edward the Seventh.
11. She has been working with the group since it began.
12. Brazil is to have its first civilian president since the military regime was set up 17 years ago.
You also use since to say either when the last time was that something happened, or how much time passes without something happening. If you are speaking on Friday and you say that you have not done something since Wednesday, or that it is two days since you did something, you mean that the last time you did that thing was on Wednesday.
13. Probably she hadn’t touched food since breakfast.
14. It was a shamefully long time since either she or Tusker had been to church.
