“…Control variables: The control variables are selected to affect both the core explanatory variable and the outcome variable as much as possible. After reviewing the literature, the following are used as the control variables: Foreign investment (Kahn et al., 2021; Zheng et al., 2017), infrastructure (Wang, 2013; Zheng et al., 2017), industrial output (Zheng et al., 2017), population (Alder et al., 2016; Kahn et al., 2021), land price (Wang, 2013), nighttime light (Alder et al., 2016), railroads (Kahn et al., 2021), and airports (Zheng et al., 2017). In addition, the policy variables that may cause bias are controlled as much as possible.…”