Describe the idea of thinking of sentences as having both a ""surface structure"" and a ""deep structure"". Also answer the following: does ""movement"" happen at surface or deep structure?

Deep structure is the underlying abstract structure that determines its semantic interpretation. Surface structure is the superficial organization of units that determines phonetic interpretation and relates to the physical form of actual oral expression, its perceived or intentional form. Important to remember that the deep and surface structure need not be identical. The underlying organization of a sentence, which is important for semantic interpretation, is not necessarily revealed by the actual arrangement and method of expression of its components.

The movement from the deep structure to the surface structure necessarily involves the process of deletion, generalization and distortion. Many important clues about the deep structure, however, are expressed and reflected in the structure of the verbal surface.