Unit 18. for since ago

BASIC GRAMMAR IN USE

 

Unit 18. for  since  ago

 

Rachel is in Brazil.

She has been there for three days.

She has been there since Monday.

 

for+a period of time	since+the start of the period
three days     10 minutes an hour     two hours a week    Four weeks a month    six months five years    a long time	Monday    Wednesday 9:00   12:30 July 4th    my birthday January    I was 10 years old 2000    we arrived
David has been in Canada for six months. (not since six month)	David has been in Canada since January. (=from January to now)
We've been waiting for two hours.	We've been waiting since 9:00.

 

ago=before now:

 

Anna started her new job three weeks ago. (=three weeks before now)

I had dinner an hour ago.

Life was very different a hundred years ago.

 

Compare ago and for:

 

When did Rachel arrive in Brazil?

She arrived in Brazil three days ago.

 

How long has she been in Brazil?

She has been in Brazil for three days.