Study on the system of civil code China 并列题名：Study on the system of civil code China study on the system of concealment in ancient China Study on the system of energy supply in China study on the transfer of rural labor in China study on the system of new rural development policy study on history of crops in China 并列题名：Study on the system of energy supply in China On the security law system of the civil code of China Study on codifaction of civil code in contemporary China