The rank-scale introduced in chapter 2 stated that a sentence consists of one or more clauses, a clause or one or more phrases, and a phrase of one or more words. But chapters 10–12 have shown that this description only works for some sentences, because clauses can be rank-shifted and function inside NPs and PrepPs, and also in the place of a phrase as subject, complement or adverbial in clause structure. We have called this the embedding of one subordinate constituent in another.