Uncountable noun or countable noun

0 see examples of both here:02br
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0500240hrefhttp://dictionary.cambridge.org/define.asp?key=79662&dict=CALD

0 Sugar is a substance, as are water, milk, wine, sand, salt, gold, silver, gasoline, oil, and air. Substances are not countable.02br
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00 CJ0-

0 But last time when i was sitting at the coffee shop. I heard some English people spoke: Would you like to have a sugar in your cup? So I thought sugar might be a countable noun, isn't it?0-

0 Also at the Cambridge link above:02br
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01i00How many sugar01b00s 02b00(00= spoonfuls or lumps of sugar)00 do you take in your tea?02br
02br
00Glucose and lactose are sugar01b00s02b00.02br
02i0-

0 So what is your conclusion? I don't get it. 0-

0'a sugar' in that sense (how many sugars, one or two sugars) is short for 'a teaspoon of sugar'. The spoons are countable, not the sugar.0-

0 01blockquote

01cite10Son_tiny12cite10So what is your conclusion? I don't get it. 12br
12blockquote

10My conclusion is that Cambridge is right in listing it as both C and U. 0-

0 I got it. Thank nona the brit and marius hancu very much. Now it is very clear to understand.0-

0 01blockquote

00 So what is your conclusion? I don't get it.12blockquote

10Whenever you talk about a substance, you are talking about something uncountable. (01i00Sugar is sweet.02i00 = The substance called sugar is sweet.). 02br
00 But when you talk about a specified amount of a substance, you treat the amount as a

my dear sugar is uncountable

for example

we say

I need some sugar