How to apply "singular count nouns need an article"?

[vgv8]

The rule "singular count nouns need an article" is very simple and would have been extremely useful.

Is it the universal rule?

I observe a lot of examples contradicting it

How to apply this rule?

[lauralie2]

The rule "singular count nouns need an article" is very simple and would have been extremely useful.

Is it the universal rule?

I observe a lot of examples contradicting it

How to apply this rule?

Let's start with the examples. Would you post them please?

[vgv8]

As an example, first jumped to my head:
- "free of charge"

Charge is countable noun

[lauralie2]

As an example, first jumped to my head:
- "free of charge"

Charge is countable noun

'Free of' means no:

• free of cost, no cost
• free of fat, no fat

'free of' and 'no' hold the same structural position; they determine the noun they modify, just like 'a/an'. Pick one, not both. If you change them into adjectives, then a determiner is required:

• free of cost
  
  • the/a free-of-cost subscription
  • the/a no-cost subscription
  
  

• free of fat
  
  • the/a free-of-fat diet
  • the/a no-fat diet
  
  

[vgv8]

Thanks a lot,
but I still did not grasp about articles after "of" and before a noun...

Should the word "interaction" be always preceded by an article in the phrase:
"... a new concept of interaction between your website visitors and the CAPTCHA..."?