The document discusses the structure of arguments in language. It defines an argument as an expression that helps complete the meaning of a predicate. Predicates take one, two, or three arguments to form a predicate-argument structure. An adjunct is an optional part of a sentence that does not affect the sentence if removed. Valency theory explores the nature of predicates, arguments, and adjuncts. Transitivity relates to whether a verb can take direct objects and how many. Selectional properties determine the semantic content of a predicate's arguments. Theta theory assigns thematic roles like agent and patient to arguments.