5.4.1 Adverbs
If an adjunct is placed between the head and its sister, i.e. the complement, the branches of the structure cross and this is not a possible configuration. The problem with this account, however, besides its reliance on the assumption that complements are all sisters to the head, is that it is not at all clear why various movement phenomena would not separate the head from its complement. Another account, due to Stowell (1981) assumes that the verb is responsible for assigning Case to the object and that there is an adjacency requirement on Case assigners and assignees. As we have assumed that the theme gets its Case from the light verb, we cannot use Case adjacency to account for why the verb and its theme argument cannot be separated. Even if we assume that Case assigners must be adjacent to the element they Case mark, this will not prevent the verb moving to a higher light verb position allowing an adverb to come between the two: