## 2 Literature Review
### Comments on Previous Research  
Based on the research status reviewed above, we can at least identify the following issues. First, the most critical problem lies in the disagreements over situation type classification, which manifests in two main aspects: the first is there is no consensus on how many categories situation types should be divided into; and the second is the hierarchical issues of situation types. [PERSON] [4] placed units such as verbs, verbal phrases and even sentences on the same level and attempted to classify them all at once, in such a way that verb situation types cannot be independent of the whole structure. Influenced by [PERSON] [4], many scholars' categorization of accomplishment situation types always include verb-object phrases, while other situation types are composed by verbs alone. To avoid conflicts, many researchers have continually elevated the level of situation types, but this approach makes it difficult to investigate the essence of lexical aspect. Second, the classification of situation types is often based on scholars' experience and intuition, which involves a certain degree of subjectivity. A crucial issue is the lack of explicit annotation standards, as many scholars categorize situation types based on the semantics of verbs rather than considering formal syntactic rules as annotation criteria. Only a few scholars, such as [PERSON] [12], determine the attribution of verb situation types based on the co-occurrence of verbs with aspectual markers. However, regardless of semantic or formal criteria, scholars have overlooked consistency checks in their research, which is also a focal point of this paper. Additionally, there is currently a lack of large-scale data validation for the classification systems. Therefore, it is essential to adopt scientific and statistical methods for research. Third, most scholars can only predict situation types at the sentence level because they cannot thoroughly analyze verb level situation types. Only a few scholars have conducted in-depth research and prediction on the situation types of verbs. However, if situation type prediction at the verb and phrasal levels cannot be achieved, predicting situation types at the sentence level is not highly meaningful. This is because the situation type of a verb may change according to the situation type of the sentence it appears in, eventually falling into the dilemma of circularity. Most scholars avoid the issue of predicting verb situation types, and the primary reason for this avoidance is not, as they often claim, that \"situation type can only be assigned to a verb phrase or sentence [5; 38]\" or that \"situation types can be shifted by the influence of other sentence components [4; 5; 39]\". Rather, it is because verbs are numerous, each with multiple senses which may change in context. This makes it necessary for researchers to consider complex factors when predicting situation types, resulting in a massive workload for comprehensive research. Therefore, only a small number of scholars have achieved thorough classification. In the study of situation types in China, only [PERSON] [12] has classified the situation types of over 1000 verbs from the _Verb Usage Dictionary_[40]. Fourth, many scholars have avoided the issue of situation type compositionality. They only acknowledge the existence of event types at the sentence level, oversimplifying the true semantic model of situation type research, and fail to recognize the independence of verb situation types. Compositionality allows verbs, verbal phrases and sentences to be placed at different levels, reflecting the recursiveness of aspectual information. If we accept the compositionality and recursiveness of aspect, then constructing a verb situation type system becomes an unavoidable task. However, since the factors involved in compositionality are relatively complex, we will address this topic in a separate paper.