Research on the Contribution Rate Level and Adjustment of China's Social Insurance System 并列题名:Research on the Contribution Rate Level and Adjustment of China's Social Insurance System Research on the evaluation of the implementation of the new type of rural social assistance system Research on the optimization of rural social endowment insurance system Research on major issues in the integration and improvements of China's social security system Research on the distribution effect of China's fiscal and taxation system Research on the optimization and development of agricultural insurance system in China Research on construction of compulsory food safety liability insurance system Studies on the contribution regimes of urban employees' basic old-age insurance system Research on the welfare distributional effects of China's social medical insurance system