Is "what a lovely paper" grammatically correct?
I know these are correct:

1) What a lovely dog!
2) What an ugly boy!

But I don't know if the subject is an uncountable noun:

3) What a good paper! (?)
4) What a cold water! (?)

Also, when it is plural:

5) What a good men! (?)
6) What a nice cars! (?)

Should each "a" of 3), 4), 5) and 6) be eliminated?

Thanks!

Question

Is "what a lovely paper" grammatically correct?
I know these are correct:

1) What a lovely dog! 
2) What an ugly boy!

But I don't know if the subject is an uncountable noun:

3) What a good paper! (?) 
4) What a cold water! (?)

Also, when it is plural:

5) What a good men! (?) 
6) What a nice cars! (?)

Should each "a" of 3), 4), 5) and 6) be eliminated?

Thanks!

Answer

If the subject is uncountable then you do not need ä"...what good paper, what cold water, HOWEVER you could  say "what a good paper" if you mean a scientific paper submitted by a professor, for example.
Plural nouns do not need the indefinitite article, so "what good men, what nice cars".