RESEARCHES ON APPLICATIONS OF NOMINALIZATION IN DIFFERENT DISCOURSES

As an important grammatical resource, nominalization has drawn many scholars’ attention, in which the most representative one is Halliday’s research on nominalization, and the breakthrough of his study is chiefly reflected in the researches about scientific discourses. Inspired by Halliday, many researchers have carried out various empirical researches on nominalization in different discourses. This study reviewed four types of empirical studies on nominalization, which are nominalization in academic discourse, nominalization in non-academic discourse, comparison of nominalization in different discourses and translation of nominalization. Through reviewing these studies, limitations concerning research methodology, research materials and analysis procedures are discussed. Finally, the analysis suggests that researchers should take all types of nominalizations into consideration and further elaborate their functions in different discourses, moreover, researches should focus more on practical significance of the study in the future and try to offer learners more advice on the use of nominalization and construction of academic writing.


Introduction
Many linguistic schools have analyzed nominalization from different perspectives, such as traditional grammar (Jespersen 1924(Jespersen , 1937, structural grammar (Bloomfield 1914), transformational-generative grammar (Chomsky 1968;Lester 1971;Simpson 1979), and cognitive grammar (Langacker 1987(Langacker , 1991Lakoff 1970;Taylor 2003). However, compared with these schools, systemic functional linguistics school carried out a more systematic and in-depth study on nominalization (Fan & Wang 2003;Matthsiessen 1995;Martin 1992). Because the breakthrough of their studies on nominalization is chiefly reflected in the researches about scientific discourses. Halliday (1996) found that a lot of nominalization existing in scientific discourses, and using nominalization can make expressions become more concise, objective and formal. Therefore, inspired by Halliday's study, a lot of scholars begin to analyze nominalization in different discourses (Liu & Lu 2004). Empirical studies mainly involve the use of nominalization in academic discourses (Zhou & Liu 2017；Biber 1998；Liardét 2016；Gao 2008; Banks 2008), the use of nominalization in advertisements, legal discourses and news reports (Tang 2007；Fowler 1991；Wang 2016, some scholars compared the use of nominalization in different kinds of discourses (Yang 2006；Wang 2003；Hadidi 2012, and a lot of Chinese scholars paid attention to the translation of nominalization (Du 2010；Zhang 2016；Huang 2009). This paper reviewed these empirical researches on nominalization and concluded some limitations concerning methodology, materials and practical significance. Finally, some suggestions are provided.

Empirical Researchers on Nominalization in Different Discourses
Inspired by Halliday's research on nominalization in scientific discourses, both scholars abroad and at home carried out diversified empirical studies on the applications of nominalization, as a result, enriching the research achievements on nominalization. Hence, this paper mainly reviews four types of empirical researches on nominalization in various discourses.

Distributive Features of Nominalization in Academic Discourses
Halliday's (2004) research on nominalization has proved that nominalization is the major resource producing high lexical density, and it possesses the features of condensed information, concise expression, compact structure and strong logic (Halliday 1994(Halliday , 2000. Hence, nominalization is often used in scientific, legal and political style, because these styles are comparatively formal (Hu 1989). Triggered by these important features, a lot of scholars began to investigate nominalizations in academic discourses in order to figure out whether nominalization is also frequently used in academic discourses. Biber et al (1999: 231) analyzed the distributive features of nominalization in academic papers, and found that nominalization occupies a large part in academic papers, which is 75%. This result indicated that nominalization is of great importance in academic discourses, for it can increase the formality of discourses, as well as improving the objectivity of discourses. Liardét (2016) employed an adapted corpus-assisted methodology and analyzed nominalizations in academic texts written by university students. In this study, nominalizations were examined quantitatively, also the nominalization patterns were investigated. Result revealed that nominalizations frequently occur in academic texts, and this result further proved that nominalization is a key feature of academic discourses. Learner tended to develop this grammatical resource even in the absence of explicit instruction into their uses. So the qualitative result implied that students had problems in using nominalization, especially for some certain patterns. Thus it required teachers to pay attention to the use of nominalization when instructing, which may equip learners to harness the full potential of deploying nominalizations and constructing academically valued texts (Liardét, 2016:28).
Chinese scholars analyzed nominalization in academic discourses as well. Zhou and Liu (2017) investigated the use and functions of nominalization in Chinese EFL learners' thesis abstracts, and figured out that nominalizations weren't frequently used in Chinese EFL learners' thesis abstracts, and the patterns of nominalization are inflexible. In introduction part and result part, nominalizations were frequently used, but when writers illustrate their research purpose, nominalizations are seldom used. Besides, in terms of function, nomianlization mainly promote the cohesion and coherence of abstracts. Gao (2008) analyzed nominalizations in medical research articles, it is found that writers used lots of nominalizations in their articles to make their expressions more objective, concise and formal.

Different Functions of Nominalization in Non-Academic Discourses
There are abundant researches on nominalization in diversified discourses, such as news report, legal discourse and advertisement discourse. Researchers intended to find the distributive features of nominalization in non-academic discourses. Fowler (1991) conducted an analysis about the feature of language used in news discourse. He found that nomianlizations are quite commonly applied in news discourse, so he further investigated the reason why nominalization plays a vital role in news discourse. As a consequence, a lot of researchers analyzed nominalization in different text due to its contributions to the concealment of ideologies, and it can conceal reporters' real ideologies by hiding the subjects and modality. Martin (1991) analyzed nominalization in a lot of different discourses, and the most important finding is that nominalization plays an important role in advertisements. It can condense room for more adjectives or modifiers, so they can modify nouns or nominal groups to make language become more vivid and persuasive. In this way, within limited sentence, adding a lot of modified language will make advertisements more attractive.
Chinese scholar Wang (2016) analyzed effects of nominalizations in legal texts from discourse level. It is found that as an important grammatical resource in legal discourses, nominalization contributes to realizing technicalization, rationalization and interpersonalization. As for technicalization, nominalization helps to create technical terms in different fields. In terms of rationalization, nominalization assists in organizing the whole text through periodicity. Regarding interpersonalization, nominalization enables language users to achieve solidarity or alienation (Wang 2016).
Tang (2007) selected 100 advertisement discourses as materials to calculate the distributions of nominalization and analyze functions of nominalization in persuading customers. Similarly, nominalization also occupied a relatively large part in advertisement discourse. From the perspective of ideational function, through nominalization, abstract status, process and human's feeling were transferred into entities, making them more concrete and prominent. In addition, writers often use nominalization in order to realize interpersonal function and increase the validity of goods through hiding subjective evaluation, in this way, convincing customers.

Similarities and Differences of Nominalization in Different Discourses
Comparisons of nominalization among different discourses are widespread. Scholars intended to find the difference in the frequency and usage of nominalization among different discourses. Martin (1991) and Bhatia (1993) compared the use of nominalization in historical, legal and advertisement discourses, the frequency of nominalization is highest in legal discourses, followed by historical discourses and the last one is advertisement discourses, at the same time, nominalization functioned distinctively in different discourses. In historical discourses, internalization of logical relationship in sentential internal structure can be achieved by nominalization. Nominalization can create more room for more modified expression by condensing information in advertisements. Finally, in legal discourses, nominalization plays an important role in making language more professional.
Hadidi (2012) carried out a comparative analysis of nominalization in business and political discourses. He found that nominalization was a striking feature of business and political discourses, and the use of nominalization can make discourse more formal, lively and valid. In business discourses, nominalization can express more information within fewer words, thus making expressions concise and diversified. While in political discourses, formal and objective language is needed, so nominalization increase the formality and objectivity of expressions, making discourses more convincing and valid.
Wang (2003) compared nominalization in five types of discourses, namely scientific discourses, legal discourses, news reports, novels and fairy tales. Results indicated that nominalization is most frequently used in legal discourses with the percentage of 83.5%, the second one comes to scientific discourses (72.6%), the third one is news reports (40.3%). However, in novels and fairy tales, nominalization seldom occurred and only accounted for 27.2% and 0.7%, respectively. As for reasons of different distribution of nominalization in these discourses, the author made a detailed interpretation. In scientific discourses, legal discourses and news reports, massive use of nominalization is helpful in increasing the objectivity, validity and conciseness of these discourses. While in novels, the majority of language are daily description or communication, hence, nominalization is inappropriate. Besides, the target readers of fairy tales are children, however, nominalization is a kind of abstract language out of its feature, so writers avoid using complex expressions since it is difficult for children to understand.
Yang (2006) made a comprehensive investigation of nominalization in Oscar Wilde's works, scientific and technical discourses and legal discourses. His study revealed that legal discourses employed lots of nominalizations in comparison with other two, and nominalization occupied 85.28%., followed by technical discourses (53.26%) and novel (10.59%). This result is in accordance with Wang's research. Yang (2006) concluded that nominalization distributed differently in different discourses, the more formal the discourses are, the more nominalizations are applied.

Translation Strategies of Nominalization in Discourses
Translation also draws many scholar's attention, hence, Chinese scholars carried out research on the translation of nominalization in various discourses. Zhang (2016) analyzed the translation of nominalization in policing English discourses, firstly she studied the functions of nominalization in discourses, which are increasing conciseness, formality and objectivity, then these results shed light on the latter study of nominalization on policing English discourses in particular. The author proposed 5 translation methods, namely literal translation, metonymy, free translation, simile and annotation. With the combination of these translation methods, translators can fully understand the implied meaning of nominalization. Thus, readers can experience the meaning of original texts. Du (2010) analyzed the structure of nominalization in legal discourses and pointed out some problems existing in the translation of nominalization in legal discourses, then raised some suggestions. First, nominalization possesses two functions in legal discourses, which are encapsulation and condensation, therefore, a nominalization contains a lot of information. Caused by different language structures and thinking patterns between the east and the west, it's difficult for Chinese to translate nominalization, because nominalization is a kind of metaphorical language. However, Chinese prefer to use congruent language, and this difference results in the problems. Based on this problem, Du claimed that translator should follow the principle of "functional equivalence" raised by Nida, clarifying the logical relationship between nominalization and other modified structures. More importantly, diluting the information density.

Quantitative Analysis Occupies A Large Part
After analyzing these empirical studies on nominalization, it can be found that the majority of studies only pay attention to the frequency of nominalization in discourses for the sake of proving that nominalization does play a vital role in various discourses. Actually, this problem is associate with the research methodology, because many scholars compile corpus by themselves and use software like AntConc or SPSS to calculate frequency or do inferential statistic. Therefore, quantitative researches on nominalization are widespread, while deeper qualitative analyses of nominalization are rare. These researches can only prove that nominalization does play a vital role in various discourses, in which the frequency and percentage can show the trend, but reasons of frequent use of nominalization in different discourses are neglected by many researchers. Most researchers spent too much time and effort on quantitative analyses, however, the qualitative discussions on nominalization are insufficient.

Explanation to Each Type of Nominalization is Unbalanced
Second, when analyzing nominalizations, most scholars made an overall investigation but failed to analyze each type of nominalization in detail, in this way, the classification of nominalization is meaningless. In addition, through reviewing these studies, it can be found that nominalization of process and nominalization of quality attract most researchers' attention (Zhu 2006). Since these two types of nominalizations occupy more than 90% of all nominalizations, the researcher emphasizes more on these two types and give enough explanation to their frequency and use. Nevertheless, nominalization of circumstance, nominalization of relator and nominalization of zero are seldom investigated and discussed. Influenced by their results, learners only know the transformational procedure of process and quality nominalization, and they still did not understand other three types, meanwhile, these three types are very difficult to explain. As a consequence, explanation to each type of nominalization is unbalanced.

Some Discourses are Incomparable
There are a lot of researches concentrating on the comparison of nominalizations in different discourses, such as legal discourses, academic discourses and news reports. They aimed to explore the relationship between the frequency of nominalization and the formality of discourse. However, the frequencies of nominalization vary differently in various discourses, and nominalizations function distinctively as well. For example, the formality of scientific discourse is relatively higher and the language used in scientific discourse is comparatively objective than others. Nominalization is a kind of grammatical resource that can increase the formality of discourse, so in scientific discourse, the frequency of nominalization is higher than others (Vyatkina 2013). But in other discourses, such as novel and fairy tale, the frequency of nominalization is lower because their language is easy to understand. Thus different genres have their own features, which will influence the distribution of nominalization in different discourses. However, many researchers usually ignore this point. As a result, some discourses are incomparable, and it's hard to analyze why nominalizations occupy different percentages or function differently.

Practical Contribution is Limited
In recent years, nominalization attracts many instructors' attention and they want to employ nominalizations in their teaching since it is difficult for EFL learners (Ryshina-Pankova 2010). Through analyzing the use of nominalization in writing by students, researchers intended to find problems or difficulties in using nominalization in their writing. Owing to the unbalanced research methodology, most studies still concentrate on the frequency of nominalization in different discourses from various disciplinary, and they seldom analyze the specific use of nominalization. Therefore, learners still do not know how to use different types of nominalization under distinct circumstances or how to use nominalization to construct academic writing (Aarts 2011). Besides, even though some researches have found problems and difficulties in using nominalization, reasons of these problems were not elaborated. The pedagogical significance of empirical researches on nominalization is limited, practical suggestions are not offered.

Suggestions for Future Studies
Based on the aforementioned limitations, some suggestions are concluded, which mainly involves advice concerning research methodology, theoretical analysis, qualitative discussion and some pedagogical meaning.

Deepen the Qualitative Discussion
Future researches should balance the research methodology, spending similar effort and time on qualitative part. After calculating the frequency of nominalization, researchers can combine the quantitative data with qualitative analysis. In this way, the data means more than a number, thus, learners can have a deeper understanding why nominalization occupy such a large part in discourses. Additionally, in-depth qualitative discussion can help learners use nominalization. Through analyzing specific examples, learners will know how nominalization can increase the formality, conciseness, objectivity and coherence of discourses (Fan 1999).

Concentrate on Each Type of Nominalization
According to Halliday's classification of nominalization, there are totally five types of nominalizations, namely, process nominalization, quality nominalization, circumstance nominalization, relator nominalization and zero nominalization. As what have been mentioned, process and quality nominalization draw much attention. Hence, other three types should get enough attention. These three types are comparatively difficult to explain than process and quality nominalization since they are seldom applied in discourses, and from theoretical perspective, their transformational procedure is complex (Bussman 2000). But they also contribute to the construction of a concise, objective and coherent discourse, so they deserve detailed elaboration. This requires researchers to read more literature reviews to find theoretical support and analyze more examples to conclude their features. In other words, researchers should concentrate on each type of nominalization.

Take Genre into Consideration
Most comparative studies explore the frequency and the use of nominalization in different discourses, but when analyzing reasons of these differences, the effect of genre was neglected. Therefore, hopefully future studies can take features of different genres into consideration when they try to interpret why nominalization distribute differently and function distinctly in different discourses. At the same time, through explaining nominalization from features of genre, learners will know what they need when using nominalization properly to write different texts. Combining genre with the use of nominalization, it can prove that whether genre will influence the distribution and usage of nominalization.

Strengthen Pedagogical Significance
The primary goal of these empirical studies on nominalization is to offer some useful and practical suggestions for future studies, teachers and learners. Previous studies did not raise many meaningful advice, thus future researchers should concentrate on the pedagogical meaning of their researches on nominalization. When they interpret their research findings, they can offer suggestions for learners about how to use nominalization to construct a more scientific and academic discourse, and give constructions to teachers about how to teach student to use nominalization and avoid some mistakes (Vasylets 2017). In this way, learners can realize the importance of nominalization and the research will be more meaningful for all the researchers and learners. Therefore, the most important advice for future study is to strengthen pedagogical significance.

Conclusion
This paper reviewed empirical studies on nominalization. Through analyzing these researches, limitations on these researches were presented and suggestions for future studies are proposed. As an important and useful lexical grammatical resource, nominalization can help writers construct a more cohesive, scientific and coherent discourse. How to use nominalizations properly and flexibly is important for researchers and learners in academic writing. Hence, future studies may analyze nominalization based on practical situation, perfect research methodology and improve pertinence. Moreover, researchers may take interdisciplinary differences into consideration when interpreting the reasons of different distribution. and strengthen pedagogical significance, thus providing more suggestions for learners and researchers.