Research on the optimum premium rate of basic medical insurance in China 并列题名：Research on the optimum premium rate of basic medical insurance in China Study on the optimal level of basic medical insurance Research on the equity of rural and urban residents basic medical insurance scheme 并列题名：Study on the optimal level of basic medical insurance Research on the optimization and development of agricultural insurance system in China Research on the common prosperity, basic medical insurance and sustainable livelihood 并列题名：Research on the equity of rural and urban residents basic medical insurance scheme Research on government responsibility position of basic endowment insurance in China Research on the development of agricultural income insurance in China