The a-trees contain the raising predicates "wants" and "judges", whereas the b-trees contain the control predicates "told" and "asked". Despite the fact that structures assumed for these different predicate types are essentially the same, there is a major distinction to be drawn. This distinction is that the control predicates semantically select their objects, whereas the raising predicates do not. In other words, the object is a semantic argument of the control predicate in each case, whereas it is not an argument of the raising predicate. This situation obtains despite the fact that both predicate types take the object to be the "subject" of the lower predicate.