Thisriverformsanatural_______betweenChinaandKorea.
A、boundarySomelazymenwouldrather_______thanwork.
Whenaspacecrafttravels,oneofthemajorproblemsisreentryintotheEarth’s_______.
Asateacher,youshouldnot_______thestudentsfromaskingquestionsinclass.
Carelessnessmadehimfallinhisjob_______.
Afterworkingfortwentyhourswithoutanyrest,thedoctorswere_______.
