What combines together to form a disaccharide? ?

A disaccharide (also called a double sugar or biose) is the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose, and maltose.
sucrose — common table sugar = glucose + fructose.lactose — major sugar in milk = glucose + galactose.maltose — product of starch digestion = glucose + glucose.