This is Everyday Grammar. I'm Kaveh.
And I'm Lucija.
Lucija, how long have you been living in the city?
I've been living here for six years. Yeah, I've been living here since 2010.
So…you've been living here for…Hmm, that's a really interesting point you just brought up.
What do you mean?
Well, the use of for and since. FOR talks about a period or duration of time. It doesn't have to be an exact number, but it needs to refer to a period of time. Like,
For the weekend
For the weekend（这个周末）
For a long time
For a long time（很长一段时间）
Wait, let me try!
We're going to New York for the weekend.
We're going to New York for the weekend.（周末我们将去纽约。）
I've known you for ages.
I've known you for ages.（我认识你很多年了。）
I have been studying English for a long time.
I have been studying English for a long time.（我学英语学了很长一段时间了。）
That's great! Also, FOR can be used when talking about the past, present or future.
Last year, I traveled for three weeks.
Last year, I traveled for three weeks.（去年，我旅行了三个星期。）
I'm traveling for three weeks.
I'm traveling for three weeks.（我正进行三周的旅行。）
Next year, I will travel for three weeks.
Next year, I will travel for three weeks.（明年，我计划旅行三个星期。）
SINCE refers to a point of time. For example,
I have lived here since 2010.
I have lived here since 2010.（自2010年以来，我就住这儿。）
It has been raining since 8 a.m.
It has been raining since 8 a.m. （上午八点开始就一直在下雨。）
I have been walking since 5 p.m.
I have been walking since 5 p.m.（下午五点开始我就在散步。）
Remember, FOR is used with a period of time. While SINCE is used to refer to a specific point in time.
And that's Everyday Grammar.