The functional group can always be found in a carbohydrate molecule. see section 5.1 ( page 109) .

The word filling the space is "hydroxyl".
The complete sentence will be as below:
The hydroxyl functional group can always be found in a carbohydrate molecule. The chemical formula of hydroxyl group OH. As the formula shows it is a bounding of Oxygen (O) and Hydrogen (H) = (OH) 

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