Deep Structure and Surface Structure
1. Derivation of syntactic structures
 two derivation distinct levels of syntactic structure
o deep structure
o surface structure
2. Deep structure (DS)
 the first level of syntactic structure
 the output of the phrase structure rules and lexical insertion (a phrase
structure tree terminating in filled lexical "slots" ) is the deep structure
(DS) of a sentence
o DS contains everything necessary for the sentence to be understood
 DS is also the input for the semantic module
o explains how the sentence is understood in terms of the lexical
material it contains and its "deep" syntactic form
3. Surface structure (SS)
 the second level of syntactic structure
 corresponds to the final syntactic form of the sentence
4. Inflection
 the final tree is checked by the inflectional submodule of the morphological
module
o inflectional rules check each word in the sentence to determine if the context
in which it is being used requires it to receive an appropriate inflectional
affix
 the verb "drink" occurs in the present tense and that its subject is
third person singular
 the inflectional affix -s is added to the verb
 this final shape serves as input to the phonological module which assigns its
pronunciation
o the phonological rules account for
 allomorphic variations (morphophonemic alternations), and
 allophonic variations
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