adj. + uncountables/ "a heavy rain" "a good information" [rule?]

[mitsuwao23]

Hi,

When I look up "a," one of the definitions says:
used before nouns that are usually uncountable when other information about the quality, feeling etc is added by anadjective, phrase, or clause:

But I am having difficulties to understand this rule. Is there any basic criterion that I can rely on to judge if this rule can be applicable?

Let's say, "rain" is usually uncountable but I think it's OK to say, "it was a heavy rain" or "a good knowledge" while I don't think you can say, "a good information" or "a expensive equipment." Why??


Thank you,
M

 

[JulianStuart]

Welcome to the forum!

The key in your question is "usually uncountable". Rain and knowledge can be used either way. However, some nouns are always uncountable: information and equipment are in that category. For those we need some kind of "counter" word : a piece of equipment, information etc. Which words are in which category is not predictable and they must, unfortunately, be learned individually.