hi Rishonly,
thank you for your reply.
You are right about this you had written, of course.
I know there is a combination : noun attribute + noun eg
a) a horse race /horse : attribute
b) a race horse / race : attribute
...but I did not mean this when writing my previous post...
To put it another way, I just had asked why one cannot say "a car door" if no specific of the four doors is meant.
I did not found such a sentence on the Internet where the expression " a car door" had been used.
Will a native English speaker say:
1) A car door had not been locked and
the car allarm went off.
Note: before the car allarm it seams to me very clear to use "the"
since there is only one car alarm in this car (at least so can we
assume).
or rather this sentence will be better for him/her?
2) The car door had not been locked and the car alarm went off.
best regards
Jacek