 One of the fundamental operations that a transformation can effect is movement, which involves shifting a part of the syntactic structure of a tree to another location within it. For example, it is often claimed that passive clauses have very much the same kinds of underlying structures as the synonymous active clauses, and thus a passive clause like (Aii) would have an underlying structure much like (T1). A movement transformation would shift the guard toward the end of the clause (and add by), and another would shift my pass into the position before the verb. In other words, passive clauses look much more like their active counterparts in underlying structure.