并列题名：Research on the quantity and composition of migrant workers' grain demand in China Research on the quantity and composition of migrant workers' grain demand in China 并列题名：Research on social protection and citizenization of migrant workers in China 并列题名：Research on economic integration of migrant population in China 并列题名：Research on the construction of community workers in China 并列题名：Research on several problems of emigrant workers in China 并列题名：Research on the Efficient Utilization of Urban Land in China 并列题名：Research on the frontiers and hotspots of regional innovation development in China 并列题名：Research on the training mode and its impact on migrant workers' income 并列题名：Research on the fair opportunity of migrant workers