Теория:

Study the main partitives.
 
Phrases with countable and uncountable nouns (pieces).
 
Remember!

A bar of chocolate

A bar of soap

A hunk of cheese

A chunk of rock
  
A cube of sugar
  
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A block of ice

A slab of concrete
  
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A rasher of bacon
  
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A clod of earth

A wad of banknotes

A slice of cake

A slice of bread

A dollop of jam
  
A lump of butter
  
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A sheet of paper

A pane of glass

A blob of paint

A trickle of rain

A drop of sauce

A puff of perfume
  
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A wisp of smoke
 
A segment of orange

A pinch of salt

A chip of china

A shred of cloth

A square of chocolate
  
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Examples:
 
I want to eat a square of chocolate.
Look! There is a segment of orange on the plate.
Give me a sheet of paper, please.
Источники:
www.theguardian.com
brokeassgourmet.com
www.theguardian.com
news.discovery.com
howdoyoudo22.com
www.corbyscatering.com.au