Thisriverformsanatural_______betweenChinaandKorea.
A、boundaryWiththe_______ofMary,allthegirlstudentsareeagertogototheparty.
Carelessnessmadehimfallinhisjob_______.
Severalloudspeakersare_______fromtheceilingandwecanhearthespeakerveryclearly.
Thedoctors_______themedicinestothepeopleinthefloodarea.
Thisriverissobigthatitisimpossibletobuilda_______underitwithoutmoderntechnology.
