Study on legal system of commercial tax in Ming dynasty 并列题名：Study on legal system of commercial tax in Ming dynasty Study on system of prime minister in Song dynasty Study on local civil trial in Song dynasty 并列题名：Study on system of prime minister in Song dynasty a study on the legal system of foreign trade during the ming and qing dynasties study on the system of concealment in ancient China Study on the post system in southwest China of the Ming dynasty Study on financial system transition of the ming dynasty Study on the issues of local social governance in the Ming dynasty