Whenaspacecrafttravels,oneofthemajorproblemsisreentryintotheEarth’s_______.
Asateacher,youshouldnot_______thestudentsfromaskingquestionsinclass.
Sometimesitisverydifficultto_______someoftheEnglishwords.Eventhenativespeakercannothelp.
Ifyouhaveanyproblemsduringyourstudyhere,pleasedonot_______tocallmeforhelp
Muchofthenewsprovidedbythisnewspaperis_______,notforeign.