Use for with periods of time: I’ve been studying English for two years.
o three years
o two weeks
o four days
o five hours
o ten minutes
o three decades
o two centuries
Use since with measuring the time after a specific point in time:
I’ve been studying English since 2010.
o last Christmas
o I was a child
o I graduated from college
As you can see from the last few examples, you don’t necessarily need to use a
specific date with since. Let’s say I graduated from college in 2004 and now it’s
2014. I could say:
▶️ I’ve been working at this company since 2004.
▶️ I’ve been working at this company since I graduated from college.
Again, since measures backwards to a specific point in time.