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(1) The gang members beat him until he lost senses (/became unconscious) and left him for dead.
(2) The gang members beat him until he lost senses (/became unconscious) and left him behind for dead.

Are the sentences correct and express the same meaning? Which is better: "lost senses" or "became unconscious"? Your comments will be appreciated. Thanks.
Comments  
I know it's commonly said but wonder if it is grammatically correct to say "for dead". As far as I know, dead is an adjective and I think for can't be followed by an adjective. It requires a noun.

I'm doing this for fun (not funny!)
Thanks in advance.
To learn someting is a fun! That's why I am here. But I am quite sure "to leave someone for dead" is okay, although I don't know how! I guess it's an "established phrase". I am looking for an expert opinion.

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AbilTo learn someting is a fun!
I would say, Learning something new is fun
That's good. I have learnt something new today.
AbilThe gang members beat him until he lost senses (/became unconscious) and left him behind for dead.
I don't think 'behind' is necessary.
Students: Are you brave enough to let our tutors analyse your pronunciation?
The gang members beat him until he lost his senses (/became unconscious) and left him for dead.

I would say:

The gang members beat him senseless and left him for dead.
Yes, no behind
Thanks Mr. Yoong, Liat, Optilang and Marius Hancu
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