## 2 Literature Review  
Existing studies are mainly conducted from three perspectives. The first perspective of research is on global trade in digital services. Higher levels of digital services significantly affect the digital service trade exports of global economies while having a negative impact on middle-income countries and no impact on low-income countries [1]. Digital service trade has a positive impact on labor income share, with a more significant positive impact on labor income share in OECD countries than in non-OECD countries, and exports of digital service trade are more conducive to increasing domestic labor income share than imports [2]. Digital service trade has a significant positive impact on the GDP of all countries; however, low and middle-income countries are lagging behind [17]. Digital service trade can have a positive impact on the high-quality development of the global manufacturing industry by promoting technological innovation and industrial structure upgrading [23]. There is an inverted U-shaped relationship between digital service trade and carbon emissions, and digital service trade increases carbon emissions by increasing emissions from digital infrastructure while reducing carbon emissions by optimizing industrial structure and adopting low-carbon technologies [24]. Overall, digital service trade has a negative impact on income inequality, which is statistically significant in high-income and middle-income countries but not significant in low-income countries [25]. Digital service trade can promote technological innovation through four mechanisms: increasing income incentives, accelerating knowledge spillovers, triggering trade liberalization, and promoting financial deepening [26]. The liberalization of digital service trade promotes the quality of green innovation in enterprises by improving human capital levels, increasing green research and development expenditures, and strengthening information resource sharing [27]. The second perspective of research is on trade networks. The scale of the global soybean trade network has expanded, and the ability of the core countries to control the global soybean trade network has gradually declined, with South America becoming the global soybean export center and Asia becoming the global soybean import center [5]. China's agricultural trade networks experienced an expansion in scale and density, with Chinapositioned at the network's center between 2000 and 2019 [6]. The four main crops, soybean, wheat, rice, and maize, showed an increasing trend in network density and regionalization, a decreasing average shortest-path length, and an increasing average clustering coefficient [7]. The global grain network is scale-free with a distinct core-periphery structure, with the core countries being the United States, Japan, Mexico, Egypt, South Korea, and Colombia, with significant heterogeneity among the nodes and greater heterogeneity in the externality than in the internality [8]. The stability and resilience of the structure of the global oil trade network have declined significantly, with reciprocal trade structures playing an important role [9]. The network size, tightness, accessibility, and reciprocity of global coal trade are all on the rise, and the reciprocity effect, the conduction closure effect, and the convergence effect contribute significantly to network construction [10]. There is a tendency for oil trade network to become progressively less connected, for gas trade network to become more connected and then less connected, for the structural resilience of oil and gas resource trade networks to become less resilient, for gas trade network to become more favorable, and for oil trade network to become more resilient than gas trade network [11]. The global crude oil trade network is expanding and becoming more connected, and five major trading blocs have been formed [12].