Uncountable nouns
Hello ! I don't understand a notion in my english book.
To give an example of uncountable nouns, they utilize this :
"Make sure you don't get a piece of glass in your foot"
But why "piece of glass" is an uncountable nouns ? I can say One piece of glass, Two piece of glass etc ...
And why me don't say "Make sure that you don't"
Pouvez-vous me répondre en français ?