I've had ths car for a month

I've done one excercise which asked to fill the blanks with "since" or "for".

For the below sentence the correct answer is "for" whereas "since" is considered false:

I've had this car ___ a month.

But couldn't we write also "I've had this car since a month" meaning that the starting point of the possession of the car was a month ago?

You could write: I have had this car since the beginning of the month.

BloodSweatTears said:

I've done [STRIKE]one[/STRIKE] an [STRIKE]excercise[/STRIKE] exercise which asked me to fill in the blanks with "since" or "for".

For the [STRIKE]below[/STRIKE] sentence below, the correct answer is "for" whereas "since" is [STRIKE]considered[/STRIKE] [STRIKE]false[/STRIKE] incorrect:

I've had this car ___ a month.

But couldn't we write also "I've had this car since a month" meaning that the starting point of the possession of the car was a month ago?

Click to expand...

Note my corrections above, and also note that you misspelt "this" in your title.

I've had this car for a month.
I've had this car for a year.
I've had this car for a week.


I've had this car since March.
I've had this car since March 7th.
I've had this car since I was 16.
I've had this car since the beginning of the year.
I've had this car since mid-March.
I've had this car since 2012.
I've had this car since yesterday.

Thank you, I have noted them.

And would "I've had this car since a month ago?" be correct?

It's unnatural. Why not stick to the many alternatives you know are correct?

Rover_KE said:

It's unnatural. Why not stick to the many alternatives you know are correct?

Click to expand...

I just want to understand on a logical level the rule which governs the use of "for" or "since".

BloodSweatTears said:

Thank you, I have noted them.

And would "I've had this car since a month ago?" be correct?

Click to expand...

Yes, grammatically.

There was a correction ems made to your post, and I'm not sure you noticed it.
Facts can be true or false.
Grammar can be correct or incorrect.

If you got the car a month ago, then writing "since a month" will still be true, even if it's not correctly written.
If you got the car a year ago, then writing "a month ago" will be false, even though it's correctly written.