It is known to us that the prepositional phrase is used quite common in linguistics and it is used for different purposes. As a matter of fact, a preposition followed by a noun phrase, such as on the hill, is a syntactic constituent, a prepositional phrase (PP), like NPs and VPs, which will be justified by four constituency tests: question/answer, structural variants of a basic sentence, reference from another word/expression, and inability to be divided by certain adverbs.

Firstly, PP is a syntactic constituent because it shapes the way a question is posed and answered. For example, the sentence that “How is Cheok getting to the airport? She’s driving by car.” can well indicate that PP shapes the way a question is posed and answered. It can be understood in this way that “to the airport” in the example is right the use of PP and this prepositional phrase has composed of the main part of the question. At the same time, the response that “by car” is another use of PP and this response perfectly answer the proposed question. Based on this, it is not hard to find that PP can definitely play a role in proposing and answering a question.

Secondly, PP can be regarded as a syntactic constituent in that it can act as a part in the sentence, like the subject, the adverbial, predictive, complement, attributive, etc. For instance, the sentence that “Gui-Fan wandered aimlessly across the unforgiving dessert” can powerfully suggest that the use of PP can serve as the adverb. Detailed speaking, “across the unforgiving dessert” is right the PP in the sentence and this phrase serves as the adverbial of place in that sentence.

Thirdly, PP is a syntactic constituent because it refers from another word or expression. It can be understood in this way that replacing the referring expression with the PP preserves the meaning of the original example. In order for better illustration, the sentence that “Ilse often calls her mother in the evenings” can be used as an example for further explanation. The more concrete condition is that “in the evenings” is the use of PP in this sentence and it can be replaced by “at nights” without changing the meaning of the whole sentence. Therefore it can effectively propose that PP is just a constituent in a sentence and it can be replaced by other phrases without making any influence to the meaning of the whole sentence.

Fourthly, the rationale why PP is a syntactic constituent lies in that it can’t be broken apart by certain adverbs. Just take the sentence “Jae put his presents on the table, but Dhiraj did not put his there” as an example. In this sentence, “on the table” is the use of PP and it will be ungrammatical when it is broken apart by the adverb. It can be understood in this way that the phrase “on there” is ungrammatical so that it should not be used in the reality.