by Liz Walter
It often seems that small, common words cause the most mistakes, and I certainly hear my students making errors with words like since, for and ago. This post therefore looks at some common errors connected with talking about periods of time and explains how to avoid them.
First, let’s look at the difference between since and for. They are both used to say how long something has been happening, but while since is followed by a precise time or a date, for is followed by a length of time:
She has lived here since 2011.
I’ve been waiting since 10 o’clock.
She has lived here for 3 years.
I’ve been waiting for over an hour.
He’s been a teacher since twenty years.
It is also common to follow since with a phrase that describes a specific time:
I’ve been playing the piano since I was five.
It’s the hottest summer since records began.
Note that when you talk about how long something has continued up to the present time or the time you are talking about, you need to use a perfect form of the verb:
I’ve known her since 1995.
I know her since 1995.
I knew her since 1995.
If you want to ask someone questions about the length of time something has existed or been happening, the most common way is to use How long …? with a perfect tense:
How long have you lived here?
How long had they known about the document?
Unlike for, since can also be used as an adverb, usually at the end of a sentence.
I met him at Jake’s party, but I haven’t seen him since.
To emphasize that a situation hasn’t changed over a period of time, we often say ever since:
She came to visit us in May, and she’s been here ever since.
He’s been grumpy ever since he arrived.
The word ago is used to say how long before the present something happened. It always comes at the end of the sentence or clause:
She called me about an hour ago.
Dinosaurs lived millions of years ago.
To talk about a period of time from its beginning to its end, we use from … to
He worked for the company from 2011 to 2014.
The course runs from May to July.
So if you’ve been struggling with these words for a long time, perhaps since you started learning Engish, which could be many years ago, I hope they will be clearer now!