Observation of course of placental separation by continuous dynamic ultrasonography during third stage of labor;

Discussion about the third problem of environmental engineering geology;

The worldwide attention is being paid to the third section because of its special role in the public field.

As to the classification of the three sections of social organizations,higher education schools should belong to the third sections,which is an education service offered to the public,an market behavior that can be freely chosen by the receivers,but not an executive behavior of the government.