Chapter 12, Problem 40P

When sucrose (common table sugar) is treated with aqueous acid, it is cleaved and yields simpler sugars of these types:

For reasons to be studied later, in the use of this procedure for the identification of the sugars incorporated in a saccharide like sucrose, the product mixtures are often treated with sodium borohydride before analysis. What limitation(s) does this put on identification of the sugar building blocks of the starting saccharide?