how long


We use for to say how long:

We have been waiting for twenty minutes.
They lived in Manchester for fifteen years.

We use since with the present perfect or the past perfect to say when something started:

I have worked here since December.
They had been watching since seven o’clock in the morning.

We use from …to/until to say when something starts and finishes:

They stayed with us from Monday to Friday.
We will be on holiday from the sixteenth until the twentieth.




Can you tell me what the main difference is in meaning or use between the following expressions : 'so far' and 'until now' (or 'up to now')? Can you give me some examples of what they mean?
Many thanks.

Hello pompeii,
Until now, I had never thought about the difference between the two! This is definitely the most complex question I've seen so far today.
In general terms, I would say that so far ​indicates that something is not finished. ​Until now, ​might indicate that something is about to change, or has already changed.
Try looking for examples in newspapers or books to give you some more help in this area.
Stephen Jones
The LearnEnglish Team

Can we write "We have been waiting since fifteen minutes ago" instead of "We have been waiting for the past fifteen minutes". The first statement isn't even making sense in my own head as I have never heard it this way before but I just wanted to know if it is correct or not. And if not, then why?

Hi piko,
Thanks for your question - it is something I hear my own students regularly getting confused with!
When we use 'since', we must use a time in the past to refer to. For example, it is now 7pm, so I could say 'We have been waiting since 6.45pm.' 
When we use 'ago', we cannot use the Present Perfect tense. So, you would have to say 'I started waiting fifteen minutes ago.'
I hope that helps to clear up the confusion. If you've never heard the language used in a certain way before, there is often a good reason!
Stephen Jones
The LearnEnglish Team

Very helpful this course, I really Like it!!!, Could you please tell me if the sentence number three in the exercise is ok... well I refer to:
I've haven't seen him.... it should be:
I haven't seen him or I have not seen him
Maybe I'm confused

Well spotted! I've changed the exercise because that sentence was wrong.
Please tell us if you spot any other problems.
Best wishes,
The LearnEnglish Team

Dear Teachers, can I begin a sentence with: Since I was born... or From 1995 to 200 ... or For x years..?

Hello Torres
Yes, you can begin sentences with these.
Since I was was born I have slept in my sister's room.
From 1995 to 2001 I lived in Leeds.
For six years I worked in a factory making biscuits. 

Does this answer your question?
I hope it helps
All the best
The LearnEnglish Team