“For”, “since” and ago are expressions that we use to talk about time

“For” “since” and “ago” are expressions that we use to talk about time and can be a little difficult for some learners of English to use correctly.

So here is a short explanation which should help you better understand how to use “for”correctly.

FOR

For is used to indicate a specific period of time.
How long are you staying at the hotel? I’m staying for a week.

For is often used with the Present Perfect.

I have been waiting at the BTS station for 10 minutes.
I have lived in this Thailand for 10 years.

For can be used with other verb tenses :
Present : I go on holidays for two weeks every summer.
Past : When I first came to Thailand, I stayed in Krabi for two months.
Future :While I am in Japan , I will be in Tokyo for 4 days.

SINCE

Since is used to refer to the starting point of actions or situations.

The period of time continues until the present. It is generally used with the Present Perfect.

I have been waiting for the train since 9 o’clock.
I live in Bangkok. I have lived in Bangkok since April 2000.
I have been learning English since the beginning of this year.

AGO

Ago is used to say when past events happened, going back from today towards the past.
The verb is in the Past Tense.

I came to Thailand ten years ago.
I arrived at the BTS station 10 minutes ago.
I graduated from university 25 years ago.

Now you should be able to use “for” “since” and “ago” correctly.

You can try these exercises.

Use of “For”, “since” and “ago”

You can practice using "for", "since" and "ago" here.