ABSTRACT
In order to understand a sentence, it is necessary to analyze it into its grammatical elements, called constituents. This analysis is known as parsing. Accomplishing this task requires knowledge of the grammar of one's native language. The fact that people are routinely in possession of this knowledge is reflected by their ability to discriminate between grammatical and ungrammatical sentences. In this regard, there is no doubt that (1a) is an acceptable English sentence, but (1b) is not.
