This paper aims at exploring the dependent clause phenomena (DCP henceforth) that is found within some Chinese prepositions. DCP is defined with reference to two aspects. Synchronically speaking, DCP refers to the phenomena that in the independent clause, a morphosyntactic category α exhibit the characteristics of a different category β but the same behavior cannot be detected in the main clause. Diachronically speaking, the degree of the language change from the source category β to the target category α is not homogeneous. Some members in α demonstrate all the morphosyntactic behaviors of β, and therefore can be viewed as has been fully evolved into B. However, some others still retain the syntactic distributions of their source category when embedded in the dependent clause. DCP reflects the heterogeneous nature of a language. It is crucial in that it facilitates the understanding of the process of grammaticalization from verb to preposition and contributes to the diagnostics of the grammatical status of some prepositions. However, little attention is paid to this phenomenon. To fill in this gap and to further illustrate this concept, we present a case study. Using Chinese prepositions anzhao (according to) and jianyu (considering) as an example, we show how certain prepositions syntactically reflect the characteristics of verbs and how these verbal properties can only be permitted in dependent clause, as required by DCP. The examination of anzhao shows that DCP exists in Modern Chinese. More specifically, according to Modern Chinese Dictionary (7th edition 2016), anzhao only has one part-of-speech, i.e. preposition; however, our investigation reveals that it can behave as a verb, as is evidenced by the fact that (1) it can function as a predicate independently; (2) it carries aspect markers; (3) it can be negated independently; and (4) it can be modified by adverbs. However, all of these obey DCP, i.e., they can only be permitted in dependent clause, but not in main clause. The investigation of jianyu supports DCP from a diachronic perspective. The prevalent view (Lü 1999; Modern Chinese Dictionary 7th edition 2016) takes this preposition as a functional word (preposition and conjunction); however, our study shows that up till the 1930s, jianyu still exhibits verbal properties: it can function as a predicate independently and take an external argument. Interestingly, these verbal properties can only be permitted in dependent clause, but not in main clause. Since the late 1940s, the DCP of jianyu has disappeared gradually, leading to the categorical shift of jianyu from verb into preposition. Based onthe two case studies, it is argued that: (1) DCP can be detected in modern synchronic period as well as historical period in Chinese. The clausal structure should be taken into consideration when distinguishing prepositions from verbs. Taking the perspective of DCP, syntactic structures where verbs can appear should be divided into two levels: main clause level and dependent clause level. The so-called verbs that have DCP are still verb, which are dependent clause verbs. (2) Decategorized features, in the process of grammaticalization from verbs into prepositions, take place initially in the main clause, and then extend to dependent clause. (3) DCP emerges through the synergy of the de-categorization effect of grammaticalization and the structure-preserving effect of dependent clause. The structure-preserving effect of dependent clause is a crucial factor that lead to the diachronically preservation of the characteristics from the old language. (4) DCP can be taken as a syntactic degradation, primarily due to the fact that Chinese lacks verbal morphology. Compared to languages that have verbal morphology such as English, Chinese is more likely to exhibit the characteristics of DCP and syntactic degradation.